diff --git a/model/histogram/float_histogram.go b/model/histogram/float_histogram.go
index 58f13c8cf3..5431892dd1 100644
--- a/model/histogram/float_histogram.go
+++ b/model/histogram/float_histogram.go
@@ -225,6 +225,9 @@ func (h *FloatHistogram) TestExpression() string {
 	if m.ZeroThreshold != 0 {
 		res = append(res, fmt.Sprintf("z_bucket_w:%g", m.ZeroThreshold))
 	}
+	if m.UsesCustomBuckets() {
+		res = append(res, fmt.Sprintf("custom_values:%g", m.CustomValues))
+	}
 
 	addBuckets := func(kind, bucketsKey, offsetKey string, buckets []float64, spans []Span) []string {
 		if len(spans) > 1 {
diff --git a/promql/parser/generated_parser.y b/promql/parser/generated_parser.y
index 841bd31c19..b39c1150a5 100644
--- a/promql/parser/generated_parser.y
+++ b/promql/parser/generated_parser.y
@@ -84,6 +84,7 @@ BUCKETS_DESC
 NEGATIVE_BUCKETS_DESC
 ZERO_BUCKET_DESC
 ZERO_BUCKET_WIDTH_DESC
+CUSTOM_VALUES_DESC
 %token histogramDescEnd
 
 // Operators.
@@ -797,6 +798,11 @@ histogram_desc_item
                    $$ = yylex.(*parser).newMap()
                    $$["z_bucket_w"] = $3
                 }
+                | CUSTOM_VALUES_DESC COLON bucket_set
+                {
+                   $$ = yylex.(*parser).newMap()
+                   $$["custom_values"] = $3
+                }
                 | BUCKETS_DESC COLON bucket_set
                 {
                    $$ = yylex.(*parser).newMap()
diff --git a/promql/parser/generated_parser.y.go b/promql/parser/generated_parser.y.go
index 3075b9b1b1..d9a312a137 100644
--- a/promql/parser/generated_parser.y.go
+++ b/promql/parser/generated_parser.y.go
@@ -67,62 +67,63 @@ const BUCKETS_DESC = 57375
 const NEGATIVE_BUCKETS_DESC = 57376
 const ZERO_BUCKET_DESC = 57377
 const ZERO_BUCKET_WIDTH_DESC = 57378
-const histogramDescEnd = 57379
-const operatorsStart = 57380
-const ADD = 57381
-const DIV = 57382
-const EQLC = 57383
-const EQL_REGEX = 57384
-const GTE = 57385
-const GTR = 57386
-const LAND = 57387
-const LOR = 57388
-const LSS = 57389
-const LTE = 57390
-const LUNLESS = 57391
-const MOD = 57392
-const MUL = 57393
-const NEQ = 57394
-const NEQ_REGEX = 57395
-const POW = 57396
-const SUB = 57397
-const AT = 57398
-const ATAN2 = 57399
-const operatorsEnd = 57400
-const aggregatorsStart = 57401
-const AVG = 57402
-const BOTTOMK = 57403
-const COUNT = 57404
-const COUNT_VALUES = 57405
-const GROUP = 57406
-const MAX = 57407
-const MIN = 57408
-const QUANTILE = 57409
-const STDDEV = 57410
-const STDVAR = 57411
-const SUM = 57412
-const TOPK = 57413
-const aggregatorsEnd = 57414
-const keywordsStart = 57415
-const BOOL = 57416
-const BY = 57417
-const GROUP_LEFT = 57418
-const GROUP_RIGHT = 57419
-const IGNORING = 57420
-const OFFSET = 57421
-const ON = 57422
-const WITHOUT = 57423
-const keywordsEnd = 57424
-const preprocessorStart = 57425
-const START = 57426
-const END = 57427
-const preprocessorEnd = 57428
-const startSymbolsStart = 57429
-const START_METRIC = 57430
-const START_SERIES_DESCRIPTION = 57431
-const START_EXPRESSION = 57432
-const START_METRIC_SELECTOR = 57433
-const startSymbolsEnd = 57434
+const CUSTOM_VALUES_DESC = 57379
+const histogramDescEnd = 57380
+const operatorsStart = 57381
+const ADD = 57382
+const DIV = 57383
+const EQLC = 57384
+const EQL_REGEX = 57385
+const GTE = 57386
+const GTR = 57387
+const LAND = 57388
+const LOR = 57389
+const LSS = 57390
+const LTE = 57391
+const LUNLESS = 57392
+const MOD = 57393
+const MUL = 57394
+const NEQ = 57395
+const NEQ_REGEX = 57396
+const POW = 57397
+const SUB = 57398
+const AT = 57399
+const ATAN2 = 57400
+const operatorsEnd = 57401
+const aggregatorsStart = 57402
+const AVG = 57403
+const BOTTOMK = 57404
+const COUNT = 57405
+const COUNT_VALUES = 57406
+const GROUP = 57407
+const MAX = 57408
+const MIN = 57409
+const QUANTILE = 57410
+const STDDEV = 57411
+const STDVAR = 57412
+const SUM = 57413
+const TOPK = 57414
+const aggregatorsEnd = 57415
+const keywordsStart = 57416
+const BOOL = 57417
+const BY = 57418
+const GROUP_LEFT = 57419
+const GROUP_RIGHT = 57420
+const IGNORING = 57421
+const OFFSET = 57422
+const ON = 57423
+const WITHOUT = 57424
+const keywordsEnd = 57425
+const preprocessorStart = 57426
+const START = 57427
+const END = 57428
+const preprocessorEnd = 57429
+const startSymbolsStart = 57430
+const START_METRIC = 57431
+const START_SERIES_DESCRIPTION = 57432
+const START_EXPRESSION = 57433
+const START_METRIC_SELECTOR = 57434
+const startSymbolsEnd = 57435
 
 var yyToknames = [...]string{
 	"$end",
@@ -161,6 +162,7 @@ var yyToknames = [...]string{
 	"NEGATIVE_BUCKETS_DESC",
 	"ZERO_BUCKET_DESC",
 	"ZERO_BUCKET_WIDTH_DESC",
+	"CUSTOM_VALUES_DESC",
 	"histogramDescEnd",
 	"operatorsStart",
 	"ADD",
@@ -235,270 +237,273 @@ var yyExca = [...]int16{
 	24, 134,
 	-2, 0,
 	-1, 58,
-	2, 171,
-	15, 171,
-	75, 171,
-	81, 171,
-	-2, 100,
-	-1, 59,
 	2, 172,
 	15, 172,
-	75, 172,
-	81, 172,
-	-2, 101,
-	-1, 60,
+	76, 172,
+	82, 172,
+	-2, 100,
+	-1, 59,
 	2, 173,
 	15, 173,
-	75, 173,
-	81, 173,
-	-2, 103,
-	-1, 61,
+	76, 173,
+	82, 173,
+	-2, 101,
+	-1, 60,
 	2, 174,
 	15, 174,
-	75, 174,
-	81, 174,
-	-2, 104,
-	-1, 62,
+	76, 174,
+	82, 174,
+	-2, 103,
+	-1, 61,
 	2, 175,
 	15, 175,
-	75, 175,
-	81, 175,
-	-2, 105,
-	-1, 63,
+	76, 175,
+	82, 175,
+	-2, 104,
+	-1, 62,
 	2, 176,
 	15, 176,
-	75, 176,
-	81, 176,
-	-2, 110,
-	-1, 64,
+	76, 176,
+	82, 176,
+	-2, 105,
+	-1, 63,
 	2, 177,
 	15, 177,
-	75, 177,
-	81, 177,
-	-2, 112,
-	-1, 65,
+	76, 177,
+	82, 177,
+	-2, 110,
+	-1, 64,
 	2, 178,
 	15, 178,
-	75, 178,
-	81, 178,
-	-2, 114,
-	-1, 66,
+	76, 178,
+	82, 178,
+	-2, 112,
+	-1, 65,
 	2, 179,
 	15, 179,
-	75, 179,
-	81, 179,
-	-2, 115,
-	-1, 67,
+	76, 179,
+	82, 179,
+	-2, 114,
+	-1, 66,
 	2, 180,
 	15, 180,
-	75, 180,
-	81, 180,
-	-2, 116,
-	-1, 68,
+	76, 180,
+	82, 180,
+	-2, 115,
+	-1, 67,
 	2, 181,
 	15, 181,
-	75, 181,
-	81, 181,
-	-2, 117,
-	-1, 69,
+	76, 181,
+	82, 181,
+	-2, 116,
+	-1, 68,
 	2, 182,
 	15, 182,
-	75, 182,
-	81, 182,
+	76, 182,
+	82, 182,
+	-2, 117,
+	-1, 69,
+	2, 183,
+	15, 183,
+	76, 183,
+	82, 183,
 	-2, 118,
 	-1, 195,
-	12, 230,
-	13, 230,
-	18, 230,
-	19, 230,
-	25, 230,
-	39, 230,
-	45, 230,
-	46, 230,
-	49, 230,
-	55, 230,
-	60, 230,
-	61, 230,
-	62, 230,
-	63, 230,
-	64, 230,
-	65, 230,
-	66, 230,
-	67, 230,
-	68, 230,
-	69, 230,
-	70, 230,
-	71, 230,
-	75, 230,
-	79, 230,
-	81, 230,
-	84, 230,
-	85, 230,
+	12, 231,
+	13, 231,
+	18, 231,
+	19, 231,
+	25, 231,
+	40, 231,
+	46, 231,
+	47, 231,
+	50, 231,
+	56, 231,
+	61, 231,
+	62, 231,
+	63, 231,
+	64, 231,
+	65, 231,
+	66, 231,
+	67, 231,
+	68, 231,
+	69, 231,
+	70, 231,
+	71, 231,
+	72, 231,
+	76, 231,
+	80, 231,
+	82, 231,
+	85, 231,
+	86, 231,
 	-2, 0,
 	-1, 196,
-	12, 230,
-	13, 230,
-	18, 230,
-	19, 230,
-	25, 230,
-	39, 230,
-	45, 230,
-	46, 230,
-	49, 230,
-	55, 230,
-	60, 230,
-	61, 230,
-	62, 230,
-	63, 230,
-	64, 230,
-	65, 230,
-	66, 230,
-	67, 230,
-	68, 230,
-	69, 230,
-	70, 230,
-	71, 230,
-	75, 230,
-	79, 230,
-	81, 230,
-	84, 230,
-	85, 230,
+	12, 231,
+	13, 231,
+	18, 231,
+	19, 231,
+	25, 231,
+	40, 231,
+	46, 231,
+	47, 231,
+	50, 231,
+	56, 231,
+	61, 231,
+	62, 231,
+	63, 231,
+	64, 231,
+	65, 231,
+	66, 231,
+	67, 231,
+	68, 231,
+	69, 231,
+	70, 231,
+	71, 231,
+	72, 231,
+	76, 231,
+	80, 231,
+	82, 231,
+	85, 231,
+	86, 231,
 	-2, 0,
 	-1, 217,
-	21, 228,
-	-2, 0,
-	-1, 285,
 	21, 229,
 	-2, 0,
+	-1, 286,
+	21, 230,
+	-2, 0,
 }
 
 const yyPrivate = 57344
 
-const yyLast = 742
+const yyLast = 778
 
 var yyAct = [...]int16{
-	151, 322, 320, 268, 327, 148, 221, 37, 187, 144,
-	281, 280, 152, 113, 77, 173, 104, 102, 101, 6,
-	128, 223, 105, 193, 155, 194, 195, 196, 339, 262,
-	260, 233, 317, 316, 57, 100, 294, 239, 103, 146,
-	300, 313, 263, 156, 156, 283, 147, 338, 259, 123,
-	337, 106, 252, 311, 155, 299, 340, 301, 264, 157,
-	157, 108, 298, 109, 235, 236, 292, 251, 237, 107,
-	155, 292, 174, 191, 175, 96, 250, 99, 258, 224,
+	151, 324, 322, 268, 329, 148, 221, 37, 187, 144,
+	282, 281, 152, 113, 77, 173, 104, 102, 101, 6,
+	223, 193, 105, 194, 195, 196, 128, 262, 260, 155,
+	233, 103, 342, 293, 100, 319, 239, 116, 146, 318,
+	315, 263, 156, 123, 106, 147, 284, 114, 295, 116,
+	156, 341, 175, 259, 340, 253, 57, 264, 157, 114,
+	117, 108, 313, 109, 235, 236, 157, 112, 237, 107,
+	323, 174, 117, 175, 155, 96, 250, 99, 293, 224,
 	226, 228, 229, 230, 238, 240, 243, 244, 245, 246,
-	247, 110, 145, 225, 227, 231, 232, 234, 241, 242,
-	98, 257, 321, 248, 249, 2, 3, 4, 5, 218,
-	158, 104, 177, 217, 168, 162, 165, 105, 175, 160,
-	164, 161, 176, 178, 189, 213, 106, 328, 216, 256,
-	183, 179, 192, 163, 181, 100, 190, 197, 198, 199,
+	247, 177, 145, 225, 227, 231, 232, 234, 241, 242,
+	98, 176, 178, 248, 249, 104, 2, 3, 4, 5,
+	158, 105, 177, 110, 168, 162, 165, 302, 150, 160,
+	191, 161, 176, 178, 189, 155, 213, 343, 106, 330,
+	72, 179, 192, 33, 181, 155, 190, 197, 198, 199,
 	200, 201, 202, 203, 204, 205, 206, 207, 208, 209,
-	210, 211, 255, 182, 72, 212, 177, 214, 215, 33,
-	82, 84, 85, 7, 86, 87, 176, 178, 90, 91,
-	223, 93, 94, 95, 116, 96, 97, 99, 83, 147,
-	233, 286, 289, 116, 114, 254, 239, 288, 147, 172,
-	220, 124, 253, 114, 171, 310, 309, 117, 120, 261,
-	98, 112, 287, 119, 278, 279, 117, 170, 282, 10,
-	308, 159, 307, 235, 236, 312, 118, 237, 147, 74,
-	306, 305, 304, 303, 302, 250, 81, 285, 224, 226,
-	228, 229, 230, 238, 240, 243, 244, 245, 246, 247,
-	79, 79, 225, 227, 231, 232, 234, 241, 242, 48,
-	78, 78, 248, 249, 122, 73, 121, 150, 180, 76,
-	290, 291, 293, 56, 295, 8, 9, 9, 34, 35,
-	1, 284, 296, 297, 155, 129, 130, 131, 132, 133,
+	210, 211, 185, 301, 258, 212, 156, 214, 215, 188,
+	256, 183, 290, 191, 252, 164, 155, 289, 300, 218,
+	223, 79, 157, 217, 7, 299, 312, 257, 163, 251,
+	233, 78, 288, 255, 182, 254, 239, 156, 216, 180,
+	220, 124, 172, 120, 147, 311, 314, 171, 119, 261,
+	287, 153, 154, 157, 279, 280, 79, 147, 283, 310,
+	170, 118, 159, 10, 235, 236, 78, 309, 237, 147,
+	308, 307, 306, 74, 76, 305, 250, 286, 304, 224,
+	226, 228, 229, 230, 238, 240, 243, 244, 245, 246,
+	247, 303, 81, 225, 227, 231, 232, 234, 241, 242,
+	48, 34, 1, 248, 249, 122, 73, 121, 285, 47,
+	291, 292, 294, 56, 296, 8, 9, 9, 46, 35,
+	45, 44, 297, 298, 127, 129, 130, 131, 132, 133,
 	134, 135, 136, 137, 138, 139, 140, 141, 142, 143,
-	47, 46, 45, 44, 156, 314, 315, 127, 43, 42,
-	41, 185, 319, 125, 166, 324, 325, 326, 188, 323,
-	157, 329, 191, 331, 330, 155, 40, 126, 332, 333,
-	100, 51, 72, 334, 53, 39, 38, 22, 52, 336,
-	49, 167, 186, 335, 54, 156, 265, 80, 341, 153,
-	154, 184, 219, 75, 115, 82, 84, 149, 70, 55,
-	222, 157, 50, 111, 18, 19, 93, 94, 20, 0,
-	96, 97, 99, 83, 71, 0, 0, 0, 0, 58,
+	43, 42, 41, 125, 166, 40, 316, 317, 126, 39,
+	38, 49, 186, 321, 338, 265, 326, 327, 328, 80,
+	325, 184, 219, 332, 331, 334, 333, 75, 115, 149,
+	335, 336, 100, 51, 72, 337, 53, 55, 222, 22,
+	52, 339, 50, 167, 111, 0, 54, 0, 0, 0,
+	0, 344, 0, 0, 0, 0, 0, 0, 82, 84,
+	0, 70, 0, 0, 0, 0, 0, 18, 19, 93,
+	94, 20, 0, 96, 97, 99, 83, 71, 0, 0,
+	0, 0, 58, 59, 60, 61, 62, 63, 64, 65,
+	66, 67, 68, 69, 0, 0, 0, 13, 98, 0,
+	0, 24, 0, 30, 0, 0, 31, 32, 36, 100,
+	51, 72, 0, 53, 267, 0, 22, 52, 0, 0,
+	0, 266, 0, 54, 0, 270, 271, 269, 276, 278,
+	275, 277, 272, 273, 274, 0, 84, 0, 70, 0,
+	0, 0, 0, 0, 18, 19, 93, 94, 20, 0,
+	96, 0, 99, 83, 71, 0, 0, 0, 0, 58,
 	59, 60, 61, 62, 63, 64, 65, 66, 67, 68,
 	69, 0, 0, 0, 13, 98, 0, 0, 24, 0,
-	30, 0, 0, 31, 32, 36, 100, 51, 72, 0,
-	53, 267, 0, 22, 52, 0, 0, 0, 266, 0,
-	54, 0, 270, 271, 269, 275, 277, 274, 276, 272,
-	273, 0, 84, 0, 70, 0, 0, 0, 0, 0,
-	18, 19, 93, 94, 20, 0, 96, 0, 99, 83,
-	71, 0, 0, 0, 0, 58, 59, 60, 61, 62,
-	63, 64, 65, 66, 67, 68, 69, 0, 0, 0,
-	13, 98, 0, 0, 24, 0, 30, 0, 0, 31,
-	32, 51, 72, 0, 53, 318, 0, 22, 52, 0,
-	0, 0, 0, 0, 54, 0, 270, 271, 269, 275,
-	277, 274, 276, 272, 273, 0, 0, 0, 70, 0,
-	0, 0, 0, 0, 18, 19, 0, 0, 20, 0,
-	0, 0, 17, 72, 71, 0, 0, 0, 22, 58,
-	59, 60, 61, 62, 63, 64, 65, 66, 67, 68,
-	69, 0, 0, 0, 13, 0, 0, 0, 24, 0,
-	30, 0, 0, 31, 32, 18, 19, 0, 0, 20,
-	0, 0, 0, 17, 33, 0, 0, 0, 0, 22,
-	11, 12, 14, 15, 16, 21, 23, 25, 26, 27,
-	28, 29, 0, 0, 0, 13, 0, 0, 0, 24,
-	0, 30, 0, 0, 31, 32, 18, 19, 0, 0,
-	20, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	0, 11, 12, 14, 15, 16, 21, 23, 25, 26,
-	27, 28, 29, 100, 0, 0, 13, 0, 0, 0,
-	24, 169, 30, 0, 0, 31, 32, 0, 0, 0,
-	0, 0, 100, 0, 0, 0, 0, 0, 82, 84,
-	85, 0, 86, 87, 88, 89, 90, 91, 92, 93,
+	30, 0, 0, 31, 32, 51, 72, 0, 53, 320,
+	0, 22, 52, 0, 0, 0, 0, 0, 54, 0,
+	270, 271, 269, 276, 278, 275, 277, 272, 273, 274,
+	0, 0, 0, 70, 0, 0, 17, 72, 0, 18,
+	19, 0, 22, 20, 0, 0, 0, 0, 0, 71,
+	0, 0, 0, 0, 58, 59, 60, 61, 62, 63,
+	64, 65, 66, 67, 68, 69, 0, 0, 0, 13,
+	18, 19, 0, 24, 20, 30, 0, 0, 31, 32,
+	0, 0, 0, 0, 0, 11, 12, 14, 15, 16,
+	21, 23, 25, 26, 27, 28, 29, 17, 33, 0,
+	13, 0, 0, 22, 24, 0, 30, 0, 0, 31,
+	32, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 18, 19, 0, 0, 20, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 11, 12, 14, 15,
+	16, 21, 23, 25, 26, 27, 28, 29, 100, 0,
+	0, 13, 0, 0, 0, 24, 169, 30, 0, 0,
+	31, 32, 0, 0, 0, 0, 0, 100, 0, 0,
+	0, 0, 0, 0, 82, 84, 85, 0, 86, 87,
+	88, 89, 90, 91, 92, 93, 94, 95, 0, 96,
+	97, 99, 83, 82, 84, 85, 0, 86, 87, 88,
+	89, 90, 91, 92, 93, 94, 95, 0, 96, 97,
+	99, 83, 100, 0, 98, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 100, 0, 98, 0, 0, 0, 0, 82, 84,
+	85, 0, 86, 87, 88, 0, 90, 91, 92, 93,
 	94, 95, 0, 96, 97, 99, 83, 82, 84, 85,
-	0, 86, 87, 88, 89, 90, 91, 92, 93, 94,
-	95, 0, 96, 97, 99, 83, 100, 0, 98, 0,
+	0, 86, 87, 0, 0, 90, 91, 0, 93, 94,
+	95, 0, 96, 97, 99, 83, 0, 0, 98, 0,
 	0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	0, 0, 0, 0, 0, 0, 0, 98, 0, 0,
-	0, 82, 84, 85, 0, 86, 87, 88, 0, 90,
-	91, 92, 93, 94, 95, 0, 96, 97, 99, 83,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	0, 98,
+	0, 0, 0, 0, 0, 0, 0, 98,
 }
 
 var yyPact = [...]int16{
-	17, 153, 541, 541, 385, 500, -1000, -1000, -1000, 146,
+	17, 164, 555, 555, 388, 494, -1000, -1000, -1000, 120,
 	-1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000,
 	-1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000,
-	-1000, -1000, -1000, 239, -1000, 224, -1000, 618, -1000, -1000,
+	-1000, -1000, -1000, 204, -1000, 240, -1000, 633, -1000, -1000,
 	-1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000,
-	36, 111, -1000, 459, -1000, 459, 141, -1000, -1000, -1000,
+	29, 113, -1000, 463, -1000, 463, 117, -1000, -1000, -1000,
 	-1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000,
-	-1000, -1000, 181, -1000, -1000, 196, -1000, -1000, 252, -1000,
-	25, -1000, -54, -54, -54, -54, -54, -54, -54, -54,
-	-54, -54, -54, -54, -54, -54, -54, -54, 37, 255,
-	209, 111, -59, -1000, 118, 118, 309, -1000, 599, 21,
-	-1000, 187, -1000, -1000, 70, 114, -1000, -1000, -1000, 238,
-	-1000, 128, -1000, 296, 459, -1000, -55, -50, -1000, 459,
-	459, 459, 459, 459, 459, 459, 459, 459, 459, 459,
-	459, 459, 459, 459, -1000, 170, -1000, -1000, -1000, 110,
-	-1000, -1000, -1000, -1000, -1000, -1000, 51, 51, 107, -1000,
-	-1000, -1000, -1000, 168, -1000, -1000, 45, -1000, 618, -1000,
-	-1000, 172, -1000, 127, -1000, -1000, -1000, -1000, -1000, 76,
-	-1000, -1000, -1000, -1000, -1000, 22, 4, 3, -1000, -1000,
-	-1000, 384, 382, 118, 118, 118, 118, 21, 21, 306,
-	306, 306, 121, 662, 306, 306, 121, 21, 21, 306,
-	21, 382, -1000, 23, -1000, -1000, -1000, 179, -1000, 180,
+	-1000, -1000, 47, -1000, -1000, 191, -1000, -1000, 253, -1000,
+	19, -1000, -49, -49, -49, -49, -49, -49, -49, -49,
+	-49, -49, -49, -49, -49, -49, -49, -49, 36, 116,
+	210, 113, -60, -1000, 163, 163, 311, -1000, 614, 20,
+	-1000, 190, -1000, -1000, 69, 48, -1000, -1000, -1000, 169,
+	-1000, 159, -1000, 147, 463, -1000, -58, -53, -1000, 463,
+	463, 463, 463, 463, 463, 463, 463, 463, 463, 463,
+	463, 463, 463, 463, -1000, 185, -1000, -1000, -1000, 111,
+	-1000, -1000, -1000, -1000, -1000, -1000, 55, 55, 167, -1000,
+	-1000, -1000, -1000, 168, -1000, -1000, 157, -1000, 633, -1000,
+	-1000, 35, -1000, 158, -1000, -1000, -1000, -1000, -1000, 152,
+	-1000, -1000, -1000, -1000, -1000, 27, 2, 1, -1000, -1000,
+	-1000, 387, 385, 163, 163, 163, 163, 20, 20, 308,
+	308, 308, 697, 678, 308, 308, 697, 20, 20, 308,
+	20, 385, -1000, 24, -1000, -1000, -1000, 198, -1000, 160,
 	-1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000,
 	-1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000,
 	-1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000, -1000,
-	-1000, -1000, 459, -1000, -1000, -1000, -1000, -1000, -1000, 52,
-	52, 10, 52, 57, 57, 38, 40, -1000, -1000, 218,
-	217, 216, 215, 214, 206, 204, 190, 189, -1000, -1000,
-	-1000, -1000, -1000, -1000, 32, 213, -1000, -1000, 19, -1000,
-	618, -1000, -1000, -1000, 52, -1000, 7, 6, 458, -1000,
-	-1000, -1000, 47, 5, 51, 51, 51, 113, 47, 113,
-	47, -1000, -1000, -1000, -1000, -1000, 52, 52, -1000, -1000,
-	-1000, 52, -1000, -1000, -1000, -1000, -1000, -1000, 51, -1000,
-	-1000, -1000, -1000, -1000, -1000, 26, -1000, 35, -1000, -1000,
-	-1000, -1000,
+	-1000, -1000, 463, -1000, -1000, -1000, -1000, -1000, -1000, 59,
+	59, 22, 59, 104, 104, 151, 100, -1000, -1000, 235,
+	222, 219, 216, 215, 214, 211, 203, 189, 170, -1000,
+	-1000, -1000, -1000, -1000, -1000, 41, 194, -1000, -1000, 18,
+	-1000, 633, -1000, -1000, -1000, 59, -1000, 13, 9, 462,
+	-1000, -1000, -1000, 14, 10, 55, 55, 55, 115, 115,
+	14, 115, 14, -1000, -1000, -1000, -1000, -1000, 59, 59,
+	-1000, -1000, -1000, 59, -1000, -1000, -1000, -1000, -1000, -1000,
+	55, -1000, -1000, -1000, -1000, -1000, -1000, -1000, 30, -1000,
+	106, -1000, -1000, -1000, -1000,
 }
 
 var yyPgo = [...]int16{
-	0, 353, 13, 352, 6, 15, 350, 263, 349, 347,
-	344, 209, 265, 343, 14, 342, 10, 11, 341, 337,
-	8, 336, 3, 4, 333, 2, 1, 0, 332, 12,
-	5, 330, 326, 18, 191, 325, 317, 7, 316, 304,
-	17, 303, 34, 300, 299, 298, 297, 293, 292, 291,
-	290, 249, 9, 271, 270, 268,
+	0, 334, 13, 332, 6, 15, 328, 263, 327, 319,
+	318, 213, 265, 317, 14, 312, 10, 11, 311, 309,
+	8, 305, 3, 4, 304, 2, 1, 0, 302, 12,
+	5, 301, 300, 18, 191, 299, 298, 7, 295, 294,
+	17, 293, 56, 292, 291, 290, 274, 271, 270, 268,
+	259, 250, 9, 258, 252, 251,
 }
 
 var yyR1 = [...]int8{
@@ -518,14 +523,14 @@ var yyR1 = [...]int8{
 	14, 14, 14, 55, 19, 19, 19, 19, 18, 18,
 	18, 18, 18, 18, 18, 18, 18, 28, 28, 28,
 	20, 20, 20, 20, 21, 21, 21, 22, 22, 22,
-	22, 22, 22, 22, 22, 22, 23, 23, 24, 24,
-	24, 3, 3, 3, 3, 3, 3, 3, 3, 3,
-	3, 3, 3, 6, 6, 6, 6, 6, 6, 6,
+	22, 22, 22, 22, 22, 22, 22, 23, 23, 24,
+	24, 24, 3, 3, 3, 3, 3, 3, 3, 3,
+	3, 3, 3, 3, 6, 6, 6, 6, 6, 6,
 	6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
 	6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
-	8, 8, 5, 5, 5, 5, 44, 27, 29, 29,
-	30, 30, 26, 25, 25, 52, 48, 10, 53, 53,
-	17, 17,
+	6, 8, 8, 5, 5, 5, 5, 44, 27, 29,
+	29, 30, 30, 26, 25, 25, 52, 48, 10, 53,
+	53, 17, 17,
 }
 
 var yyR2 = [...]int8{
@@ -545,52 +550,52 @@ var yyR2 = [...]int8{
 	3, 2, 1, 2, 0, 3, 2, 1, 1, 3,
 	1, 3, 4, 1, 3, 5, 5, 1, 1, 1,
 	4, 3, 3, 2, 3, 1, 2, 3, 3, 3,
-	3, 3, 3, 3, 3, 3, 4, 3, 3, 1,
-	2, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+	3, 3, 3, 3, 3, 3, 3, 4, 3, 3,
+	1, 2, 1, 1, 1, 1, 1, 1, 1, 1,
 	1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 	1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 	1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1, 2, 2,
-	1, 1, 1, 2, 1, 1, 1, 1, 0, 1,
-	0, 1,
+	1, 1, 1, 1, 1, 1, 1, 1, 1, 2,
+	2, 1, 1, 1, 2, 1, 1, 1, 1, 0,
+	1, 0, 1,
 }
 
 var yyChk = [...]int16{
-	-1000, -54, 88, 89, 90, 91, 2, 10, -12, -7,
-	-11, 60, 61, 75, 62, 63, 64, 12, 45, 46,
-	49, 65, 18, 66, 79, 67, 68, 69, 70, 71,
-	81, 84, 85, 13, -55, -12, 10, -37, -32, -35,
+	-1000, -54, 89, 90, 91, 92, 2, 10, -12, -7,
+	-11, 61, 62, 76, 63, 64, 65, 12, 46, 47,
+	50, 66, 18, 67, 80, 68, 69, 70, 71, 72,
+	82, 85, 86, 13, -55, -12, 10, -37, -32, -35,
 	-38, -43, -44, -45, -47, -48, -49, -50, -51, -31,
-	-3, 12, 19, 15, 25, -8, -7, -42, 60, 61,
-	62, 63, 64, 65, 66, 67, 68, 69, 70, 71,
-	39, 55, 13, -51, -11, -13, 20, -14, 12, 2,
-	-19, 2, 39, 57, 40, 41, 43, 44, 45, 46,
-	47, 48, 49, 50, 51, 52, 54, 55, 79, 56,
-	14, -33, -40, 2, 75, 81, 15, -40, -37, -37,
+	-3, 12, 19, 15, 25, -8, -7, -42, 61, 62,
+	63, 64, 65, 66, 67, 68, 69, 70, 71, 72,
+	40, 56, 13, -51, -11, -13, 20, -14, 12, 2,
+	-19, 2, 40, 58, 41, 42, 44, 45, 46, 47,
+	48, 49, 50, 51, 52, 53, 55, 56, 80, 57,
+	14, -33, -40, 2, 76, 82, 15, -40, -37, -37,
 	-42, -1, 20, -2, 12, -10, 2, 25, 20, 7,
-	2, 4, 2, 24, -34, -41, -36, -46, 74, -34,
+	2, 4, 2, 24, -34, -41, -36, -46, 75, -34,
 	-34, -34, -34, -34, -34, -34, -34, -34, -34, -34,
-	-34, -34, -34, -34, -52, 55, 2, 9, -30, -9,
-	2, -27, -29, 84, 85, 19, 39, 55, -52, 2,
+	-34, -34, -34, -34, -52, 56, 2, 9, -30, -9,
+	2, -27, -29, 85, 86, 19, 40, 56, -52, 2,
 	-40, -33, -16, 15, 2, -16, -39, 22, -37, 22,
-	20, 7, 2, -5, 2, 4, 52, 42, 53, -5,
+	20, 7, 2, -5, 2, 4, 53, 43, 54, -5,
 	20, -14, 25, 2, -18, 5, -28, -20, 12, -27,
-	-29, 16, -37, 78, 80, 76, 77, -37, -37, -37,
+	-29, 16, -37, 79, 81, 77, 78, -37, -37, -37,
 	-37, -37, -37, -37, -37, -37, -37, -37, -37, -37,
 	-37, -37, -52, 15, -27, -27, 21, 6, 2, -15,
-	22, -4, -6, 2, 60, 74, 61, 75, 62, 63,
-	64, 76, 77, 12, 78, 45, 46, 49, 65, 18,
-	66, 79, 80, 67, 68, 69, 70, 71, 84, 85,
-	57, 22, 7, 20, -2, 25, 2, 25, 2, 26,
-	26, -29, 26, 39, 55, -21, 24, 17, -22, 30,
-	28, 29, 35, 36, 33, 31, 34, 32, -16, -16,
-	-17, -16, -17, 22, -53, -52, 2, 22, 7, 2,
-	-37, -26, 19, -26, 26, -26, -20, -20, 24, 17,
-	2, 17, 6, 6, 6, 6, 6, 6, 6, 6,
-	6, 21, 2, 22, -4, -26, 26, 26, 17, -22,
-	-25, 55, -26, -30, -27, -27, -27, -23, 14, -25,
-	-23, -25, -26, -26, -26, -24, -27, 24, 21, 2,
-	21, -27,
+	22, -4, -6, 2, 61, 75, 62, 76, 63, 64,
+	65, 77, 78, 12, 79, 46, 47, 50, 66, 18,
+	67, 80, 81, 68, 69, 70, 71, 72, 85, 86,
+	58, 22, 7, 20, -2, 25, 2, 25, 2, 26,
+	26, -29, 26, 40, 56, -21, 24, 17, -22, 30,
+	28, 29, 35, 36, 37, 33, 31, 34, 32, -16,
+	-16, -17, -16, -17, 22, -53, -52, 2, 22, 7,
+	2, -37, -26, 19, -26, 26, -26, -20, -20, 24,
+	17, 2, 17, 6, 6, 6, 6, 6, 6, 6,
+	6, 6, 6, 21, 2, 22, -4, -26, 26, 26,
+	17, -22, -25, 56, -26, -30, -27, -27, -27, -23,
+	14, -23, -25, -23, -25, -26, -26, -26, -24, -27,
+	24, 21, 2, 21, -27,
 }
 
 var yyDef = [...]int16{
@@ -599,36 +604,36 @@ var yyDef = [...]int16{
 	109, 110, 111, 112, 113, 114, 115, 116, 117, 118,
 	119, 120, 121, 0, 2, -2, 3, 4, 8, 9,
 	10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
-	0, 106, 216, 0, 226, 0, 83, 84, -2, -2,
+	0, 106, 217, 0, 227, 0, 83, 84, -2, -2,
 	-2, -2, -2, -2, -2, -2, -2, -2, -2, -2,
-	210, 211, 0, 5, 98, 0, 124, 127, 0, 132,
+	211, 212, 0, 5, 98, 0, 124, 127, 0, 132,
 	133, 137, 43, 43, 43, 43, 43, 43, 43, 43,
 	43, 43, 43, 43, 43, 43, 43, 43, 0, 0,
 	0, 0, 22, 23, 0, 0, 0, 60, 0, 81,
-	82, 0, 87, 89, 0, 93, 97, 227, 122, 0,
+	82, 0, 87, 89, 0, 93, 97, 228, 122, 0,
 	128, 0, 131, 136, 0, 42, 47, 48, 44, 0,
 	0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	0, 0, 0, 0, 67, 0, 69, 225, 70, 0,
-	72, 220, 221, 73, 74, 217, 0, 0, 0, 80,
+	0, 0, 0, 0, 67, 0, 69, 226, 70, 0,
+	72, 221, 222, 73, 74, 218, 0, 0, 0, 80,
 	20, 21, 24, 0, 54, 25, 0, 62, 64, 66,
-	85, 0, 90, 0, 96, 212, 213, 214, 215, 0,
+	85, 0, 90, 0, 96, 213, 214, 215, 216, 0,
 	123, 126, 129, 130, 135, 138, 140, 143, 147, 148,
 	149, 0, 26, 0, 0, -2, -2, 27, 28, 29,
 	30, 31, 32, 33, 34, 35, 36, 37, 38, 39,
-	40, 41, 68, 0, 218, 219, 75, -2, 79, 0,
-	53, 56, 58, 59, 183, 184, 185, 186, 187, 188,
-	189, 190, 191, 192, 193, 194, 195, 196, 197, 198,
-	199, 200, 201, 202, 203, 204, 205, 206, 207, 208,
-	209, 61, 65, 86, 88, 91, 95, 92, 94, 0,
+	40, 41, 68, 0, 219, 220, 75, -2, 79, 0,
+	53, 56, 58, 59, 184, 185, 186, 187, 188, 189,
+	190, 191, 192, 193, 194, 195, 196, 197, 198, 199,
+	200, 201, 202, 203, 204, 205, 206, 207, 208, 209,
+	210, 61, 65, 86, 88, 91, 95, 92, 94, 0,
 	0, 0, 0, 0, 0, 0, 0, 153, 155, 0,
-	0, 0, 0, 0, 0, 0, 0, 0, 45, 46,
-	49, 231, 50, 71, 0, -2, 78, 51, 0, 57,
-	63, 139, 222, 141, 0, 144, 0, 0, 0, 151,
-	156, 152, 0, 0, 0, 0, 0, 0, 0, 0,
-	0, 76, 77, 52, 55, 142, 0, 0, 150, 154,
-	157, 0, 224, 158, 159, 160, 161, 162, 0, 163,
-	164, 165, 145, 146, 223, 0, 169, 0, 167, 170,
-	166, 168,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 45,
+	46, 49, 232, 50, 71, 0, -2, 78, 51, 0,
+	57, 63, 139, 223, 141, 0, 144, 0, 0, 0,
+	151, 156, 152, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 76, 77, 52, 55, 142, 0, 0,
+	150, 154, 157, 0, 225, 158, 159, 160, 161, 162,
+	0, 163, 164, 165, 166, 145, 146, 224, 0, 170,
+	0, 168, 171, 167, 169,
 }
 
 var yyTok1 = [...]int8{
@@ -645,7 +650,7 @@ var yyTok2 = [...]int8{
 	62, 63, 64, 65, 66, 67, 68, 69, 70, 71,
 	72, 73, 74, 75, 76, 77, 78, 79, 80, 81,
 	82, 83, 84, 85, 86, 87, 88, 89, 90, 91,
-	92,
+	92, 93,
 }
 
 var yyTok3 = [...]int8{
@@ -1738,47 +1743,53 @@ yydefault:
 		yyDollar = yyS[yypt-3 : yypt+1]
 		{
 			yyVAL.descriptors = yylex.(*parser).newMap()
-			yyVAL.descriptors["buckets"] = yyDollar[3].bucket_set
+			yyVAL.descriptors["custom_values"] = yyDollar[3].bucket_set
 		}
 	case 163:
 		yyDollar = yyS[yypt-3 : yypt+1]
 		{
 			yyVAL.descriptors = yylex.(*parser).newMap()
-			yyVAL.descriptors["offset"] = yyDollar[3].int
+			yyVAL.descriptors["buckets"] = yyDollar[3].bucket_set
 		}
 	case 164:
 		yyDollar = yyS[yypt-3 : yypt+1]
 		{
 			yyVAL.descriptors = yylex.(*parser).newMap()
-			yyVAL.descriptors["n_buckets"] = yyDollar[3].bucket_set
+			yyVAL.descriptors["offset"] = yyDollar[3].int
 		}
 	case 165:
 		yyDollar = yyS[yypt-3 : yypt+1]
 		{
 			yyVAL.descriptors = yylex.(*parser).newMap()
-			yyVAL.descriptors["n_offset"] = yyDollar[3].int
+			yyVAL.descriptors["n_buckets"] = yyDollar[3].bucket_set
 		}
 	case 166:
-		yyDollar = yyS[yypt-4 : yypt+1]
+		yyDollar = yyS[yypt-3 : yypt+1]
 		{
-			yyVAL.bucket_set = yyDollar[2].bucket_set
+			yyVAL.descriptors = yylex.(*parser).newMap()
+			yyVAL.descriptors["n_offset"] = yyDollar[3].int
 		}
 	case 167:
-		yyDollar = yyS[yypt-3 : yypt+1]
+		yyDollar = yyS[yypt-4 : yypt+1]
 		{
 			yyVAL.bucket_set = yyDollar[2].bucket_set
 		}
 	case 168:
 		yyDollar = yyS[yypt-3 : yypt+1]
 		{
-			yyVAL.bucket_set = append(yyDollar[1].bucket_set, yyDollar[3].float)
+			yyVAL.bucket_set = yyDollar[2].bucket_set
 		}
 	case 169:
+		yyDollar = yyS[yypt-3 : yypt+1]
+		{
+			yyVAL.bucket_set = append(yyDollar[1].bucket_set, yyDollar[3].float)
+		}
+	case 170:
 		yyDollar = yyS[yypt-1 : yypt+1]
 		{
 			yyVAL.bucket_set = []float64{yyDollar[1].float}
 		}
-	case 216:
+	case 217:
 		yyDollar = yyS[yypt-1 : yypt+1]
 		{
 			yyVAL.node = &NumberLiteral{
@@ -1786,22 +1797,22 @@ yydefault:
 				PosRange: yyDollar[1].item.PositionRange(),
 			}
 		}
-	case 217:
+	case 218:
 		yyDollar = yyS[yypt-1 : yypt+1]
 		{
 			yyVAL.float = yylex.(*parser).number(yyDollar[1].item.Val)
 		}
-	case 218:
+	case 219:
 		yyDollar = yyS[yypt-2 : yypt+1]
 		{
 			yyVAL.float = yyDollar[2].float
 		}
-	case 219:
+	case 220:
 		yyDollar = yyS[yypt-2 : yypt+1]
 		{
 			yyVAL.float = -yyDollar[2].float
 		}
-	case 222:
+	case 223:
 		yyDollar = yyS[yypt-1 : yypt+1]
 		{
 			var err error
@@ -1810,17 +1821,17 @@ yydefault:
 				yylex.(*parser).addParseErrf(yyDollar[1].item.PositionRange(), "invalid repetition in series values: %s", err)
 			}
 		}
-	case 223:
+	case 224:
 		yyDollar = yyS[yypt-2 : yypt+1]
 		{
 			yyVAL.int = -int64(yyDollar[2].uint)
 		}
-	case 224:
+	case 225:
 		yyDollar = yyS[yypt-1 : yypt+1]
 		{
 			yyVAL.int = int64(yyDollar[1].uint)
 		}
-	case 225:
+	case 226:
 		yyDollar = yyS[yypt-1 : yypt+1]
 		{
 			var err error
@@ -1829,7 +1840,7 @@ yydefault:
 				yylex.(*parser).addParseErr(yyDollar[1].item.PositionRange(), err)
 			}
 		}
-	case 226:
+	case 227:
 		yyDollar = yyS[yypt-1 : yypt+1]
 		{
 			yyVAL.node = &StringLiteral{
@@ -1837,7 +1848,7 @@ yydefault:
 				PosRange: yyDollar[1].item.PositionRange(),
 			}
 		}
-	case 227:
+	case 228:
 		yyDollar = yyS[yypt-1 : yypt+1]
 		{
 			yyVAL.item = Item{
@@ -1846,12 +1857,12 @@ yydefault:
 				Val: yylex.(*parser).unquoteString(yyDollar[1].item.Val),
 			}
 		}
-	case 228:
+	case 229:
 		yyDollar = yyS[yypt-0 : yypt+1]
 		{
 			yyVAL.duration = 0
 		}
-	case 230:
+	case 231:
 		yyDollar = yyS[yypt-0 : yypt+1]
 		{
 			yyVAL.strings = nil
diff --git a/promql/parser/lex.go b/promql/parser/lex.go
index 4e3de2a668..6da3fe6e25 100644
--- a/promql/parser/lex.go
+++ b/promql/parser/lex.go
@@ -135,15 +135,16 @@ var key = map[string]ItemType{
 }
 
 var histogramDesc = map[string]ItemType{
-	"sum":        SUM_DESC,
-	"count":      COUNT_DESC,
-	"schema":     SCHEMA_DESC,
-	"offset":     OFFSET_DESC,
-	"n_offset":   NEGATIVE_OFFSET_DESC,
-	"buckets":    BUCKETS_DESC,
-	"n_buckets":  NEGATIVE_BUCKETS_DESC,
-	"z_bucket":   ZERO_BUCKET_DESC,
-	"z_bucket_w": ZERO_BUCKET_WIDTH_DESC,
+	"sum":           SUM_DESC,
+	"count":         COUNT_DESC,
+	"schema":        SCHEMA_DESC,
+	"offset":        OFFSET_DESC,
+	"n_offset":      NEGATIVE_OFFSET_DESC,
+	"buckets":       BUCKETS_DESC,
+	"n_buckets":     NEGATIVE_BUCKETS_DESC,
+	"z_bucket":      ZERO_BUCKET_DESC,
+	"z_bucket_w":    ZERO_BUCKET_WIDTH_DESC,
+	"custom_values": CUSTOM_VALUES_DESC,
 }
 
 // ItemTypeStr is the default string representations for common Items. It does not
diff --git a/promql/parser/parse.go b/promql/parser/parse.go
index 104b80ce52..f3fa27f84e 100644
--- a/promql/parser/parse.go
+++ b/promql/parser/parse.go
@@ -566,6 +566,15 @@ func (p *parser) buildHistogramFromMap(desc *map[string]interface{}) *histogram.
 			p.addParseErrf(p.yyParser.lval.item.PositionRange(), "error parsing z_bucket_w number: %v", val)
 		}
 	}
+	val, ok = (*desc)["custom_values"]
+	if ok {
+		customValues, ok := val.([]float64)
+		if ok {
+			output.CustomValues = customValues
+		} else {
+			p.addParseErrf(p.yyParser.lval.item.PositionRange(), "error parsing custom_values: %v", val)
+		}
+	}
 
 	buckets, spans := p.buildHistogramBucketsAndSpans(desc, "buckets", "offset")
 	output.PositiveBuckets = buckets
diff --git a/promql/test.go b/promql/test.go
index 6fe233b6f4..da42468022 100644
--- a/promql/test.go
+++ b/promql/test.go
@@ -46,8 +46,8 @@ var (
 
 	patSpace                    = regexp.MustCompile("[\t ]+")
 	patLoad                     = regexp.MustCompile(`^load(?:_(with_nhcb))?\s+(.+?)$`)
-	patEvalInstant              = regexp.MustCompile(`^eval(?:_(with_nhcb))?(?:_(fail|ordered))?\s+instant\s+(?:at\s+(.+?))?\s+(.+)$`)
-	patEvalRange                = regexp.MustCompile(`^eval(?:_(fail))?\s+range\s+from\s+(.+)\s+to\s+(.+)\s+step\s+(.+?)\s+(.+)$`)
+	patEvalInstant              = regexp.MustCompile(`^eval(?:_(with_nhcb))?(?:_(fail|warn|ordered))?\s+instant\s+(?:at\s+(.+?))?\s+(.+)$`)
+	patEvalRange                = regexp.MustCompile(`^eval(?:_(fail|warn))?\s+range\s+from\s+(.+)\s+to\s+(.+)\s+step\s+(.+?)\s+(.+)$`)
 	histogramBucketReplacements = []struct {
 		pattern *regexp.Regexp
 		repl    string
@@ -233,7 +233,7 @@ func (t *test) parseEval(lines []string, i int) (int, *evalCmd, error) {
 	rangeParts := patEvalRange.FindStringSubmatch(lines[i])
 
 	if instantParts == nil && rangeParts == nil {
-		return i, nil, raise(i, "invalid evaluation command. Must be either 'eval[_with_nhcb][_fail|_ordered] instant [at <offset:duration>] <query>' or 'eval[_fail] range from <from> to <to> step <step> <query>'")
+		return i, nil, raise(i, "invalid evaluation command. Must be either 'eval[_with_nhcb][_fail|_warn|_ordered] instant [at <offset:duration>] <query>' or 'eval[_fail|_warn] range from <from> to <to> step <step> <query>'")
 	}
 
 	isInstant := instantParts != nil
@@ -314,6 +314,8 @@ func (t *test) parseEval(lines []string, i int) (int, *evalCmd, error) {
 		cmd.ordered = true
 	case "fail":
 		cmd.fail = true
+	case "warn":
+		cmd.warn = true
 	}
 	cmd.withNhcb = withNhcb
 
@@ -636,9 +638,9 @@ type evalCmd struct {
 	step  time.Duration
 	line  int
 
-	isRange       bool // if false, instant query
-	fail, ordered bool
-	withNhcb      bool
+	isRange             bool // if false, instant query
+	fail, warn, ordered bool
+	withNhcb            bool
 
 	metrics  map[uint64]labels.Labels
 	expected map[uint64]entry
@@ -965,6 +967,13 @@ func (t *test) execRangeEval(cmd *evalCmd, engine QueryEngine) error {
 		return fmt.Errorf("error creating range query for %q (line %d): %w", cmd.expr, cmd.line, err)
 	}
 	res := q.Exec(t.context)
+	countWarnings, _ := res.Warnings.CountWarningsAndInfo()
+	if !cmd.warn && countWarnings > 0 {
+		return fmt.Errorf("unexpected warnings evaluating query %q (line %d): %v", cmd.expr, cmd.line, res.Warnings)
+	}
+	if cmd.warn && countWarnings == 0 {
+		return fmt.Errorf("expected warnings evaluating query %q (line %d) but got none", cmd.expr, cmd.line)
+	}
 	if res.Err != nil {
 		if cmd.fail {
 			return nil
@@ -996,7 +1005,7 @@ func (t *test) execInstantEval(cmd *evalCmd, engine QueryEngine) error {
 		}
 		if cmd.withNhcb {
 			if !strings.Contains(iq.expr, "_bucket") {
-				return fmt.Errorf("expected _bucket in the expression %q", iq.expr)
+				return fmt.Errorf("expected '_bucket' in the expression %q", iq.expr)
 			}
 			for _, rep := range histogramBucketReplacements {
 				iq.expr = rep.pattern.ReplaceAllString(iq.expr, rep.repl)
@@ -1016,6 +1025,13 @@ func (t *test) runInstantQuery(iq atModifierTestCase, cmd *evalCmd, engine Query
 	}
 	defer q.Close()
 	res := q.Exec(t.context)
+	countWarnings, _ := res.Warnings.CountWarningsAndInfo()
+	if !cmd.warn && countWarnings > 0 {
+		return fmt.Errorf("unexpected warnings evaluating query %q (line %d): %v", iq.expr, cmd.line, res.Warnings)
+	}
+	if cmd.warn && countWarnings == 0 {
+		return fmt.Errorf("expected warnings evaluating query %q (line %d) but got none", iq.expr, cmd.line)
+	}
 	if res.Err != nil {
 		if cmd.fail {
 			return nil
diff --git a/promql/testdata/aggregators.test b/promql/testdata/aggregators.test
index 8709b393b2..86336a5d9d 100644
--- a/promql/testdata/aggregators.test
+++ b/promql/testdata/aggregators.test
@@ -399,7 +399,7 @@ eval instant at 1m quantile without(point)((scalar(foo)), data)
 	{test="three samples"} 1.6
 	{test="uneven samples"} 2.8
 
-eval instant at 1m quantile without(point)(NaN, data)
+eval_warn instant at 1m quantile without(point)(NaN, data)
     {test="two samples"} NaN
     {test="three samples"} NaN
     {test="uneven samples"} NaN
diff --git a/promql/testdata/functions.test b/promql/testdata/functions.test
index e01c75a7f6..d68a1f2f52 100644
--- a/promql/testdata/functions.test
+++ b/promql/testdata/functions.test
@@ -830,17 +830,17 @@ eval instant at 1m quantile_over_time(1, data[1m])
 	{test="three samples"} 2
 	{test="uneven samples"} 4
 
-eval instant at 1m quantile_over_time(-1, data[1m])
+eval_warn instant at 1m quantile_over_time(-1, data[1m])
 	{test="two samples"} -Inf
 	{test="three samples"} -Inf
 	{test="uneven samples"} -Inf
 
-eval instant at 1m quantile_over_time(2, data[1m])
+eval_warn instant at 1m quantile_over_time(2, data[1m])
 	{test="two samples"} +Inf
 	{test="three samples"} +Inf
 	{test="uneven samples"} +Inf
 
-eval instant at 1m (quantile_over_time(2, (data[1m])))
+eval_warn instant at 1m (quantile_over_time(2, (data[1m])))
 	{test="two samples"} +Inf
 	{test="three samples"} +Inf
 	{test="uneven samples"} +Inf
diff --git a/promql/testdata/histograms.test b/promql/testdata/histograms.test
index 0aab3117dc..b7214cfade 100644
--- a/promql/testdata/histograms.test
+++ b/promql/testdata/histograms.test
@@ -127,17 +127,17 @@ eval_with_nhcb instant at 50m histogram_quantile(1, testhistogram3_bucket)
 	{start="negative"} -0.1
 
 # Quantile too low.
-eval_with_nhcb instant at 50m histogram_quantile(-0.1, testhistogram_bucket)
+eval_with_nhcb_warn instant at 50m histogram_quantile(-0.1, testhistogram_bucket)
 	{start="positive"} -Inf
 	{start="negative"} -Inf
 
 # Quantile too high.
-eval_with_nhcb instant at 50m histogram_quantile(1.01, testhistogram_bucket)
+eval_with_nhcb_warn instant at 50m histogram_quantile(1.01, testhistogram_bucket)
 	{start="positive"} +Inf
 	{start="negative"} +Inf
 
 # Quantile invalid.
-eval_with_nhcb instant at 50m histogram_quantile(NaN, testhistogram_bucket)
+eval_with_nhcb_warn instant at 50m histogram_quantile(NaN, testhistogram_bucket)
 	{start="positive"} NaN
 	{start="negative"} NaN
 
@@ -254,6 +254,9 @@ eval_with_nhcb instant at 50m histogram_quantile(0.5, rate(request_duration_seco
 	{instance="ins1", job="job2"} 0.1
 	{instance="ins2", job="job2"} 0.11666666666666667
 
+eval instant at 50m sum(request_duration_seconds)
+	{} {{schema:-53 count:250 custom_values:[0.1 0.2] buckets:[100 90 60]}}
+
 # A histogram with nonmonotonic bucket counts. This may happen when recording
 # rule evaluation or federation races scrape ingestion, causing some buckets
 # counts to be derived from fewer samples.
diff --git a/promql/testdata/native_histograms.test b/promql/testdata/native_histograms.test
index 1da68a385f..a4fc3d8403 100644
--- a/promql/testdata/native_histograms.test
+++ b/promql/testdata/native_histograms.test
@@ -269,3 +269,18 @@ eval instant at 50m histogram_sum(sum(incr_sum_histogram))
 
 eval instant at 50m histogram_sum(sum(last_over_time(incr_sum_histogram[5m])))
     {} 30
+
+
+
+# Test native histograms with custom buckets.
+load 5m
+	custom_buckets_histogram	{{schema:-53 sum:5 count:4 custom_values:[5 10] buckets:[1 2 1]}}x10
+
+eval instant at 5m histogram_fraction(5, 10, custom_buckets_histogram)
+	{} 0.5
+
+eval instant at 5m histogram_quantile(0.5, custom_buckets_histogram)
+	{} 7.5
+
+eval instant at 5m sum(custom_buckets_histogram)
+	{} {{schema:-53 sum:5 count:4 custom_values:[5 10] buckets:[1 2 1]}}
diff --git a/util/annotations/annotations.go b/util/annotations/annotations.go
index f5f60ba874..6415f44744 100644
--- a/util/annotations/annotations.go
+++ b/util/annotations/annotations.go
@@ -94,6 +94,19 @@ func (a Annotations) AsStrings(query string, maxAnnos int) []string {
 	return arr
 }
 
+func (a Annotations) CountWarningsAndInfo() (int, int) {
+	var countWarnings, countInfo int
+	for _, err := range a {
+		if errors.Is(err, PromQLWarning) {
+			countWarnings++
+		}
+		if errors.Is(err, PromQLInfo) {
+			countInfo++
+		}
+	}
+	return countWarnings, countInfo
+}
+
 //nolint:revive // error-naming.
 var (
 	// Currently there are only 2 types, warnings and info.