diff --git a/promql/promqltest/testdata/aggregators.test b/promql/promqltest/testdata/aggregators.test
index 2fee20e630..7698d5acaf 100644
--- a/promql/promqltest/testdata/aggregators.test
+++ b/promql/promqltest/testdata/aggregators.test
@@ -462,19 +462,34 @@ load 10s
 	data{test="uneven samples",point="a"} 0
 	data{test="uneven samples",point="b"} 1
 	data{test="uneven samples",point="c"} 4
+	data{test="NaN sample",point="a"} 0
+	data{test="NaN sample",point="b"} 1
+	data{test="NaN sample",point="c"} NaN
 	data_histogram{test="histogram sample", point="c"} {{schema:2 count:4 sum:10 buckets:[1 0 0 0 1 0 0 1 1]}}
 	foo 0 1 0 1 0 1 0.8
 
+# 80th percentile.
+# The NaN sample is treated as the smallest possible value.
 eval instant at 1m quantile without(point)(0.8, data)
 	{test="two samples"} 0.8
 	{test="three samples"} 1.6
 	{test="uneven samples"} 2.8
+	{test="NaN sample"} 0.6
+
+# 20th percentile.
+# A quantile between NaN and 0 is interpolated as NaN.
+eval instant at 1m quantile without(point)(0.2, data)
+	{test="two samples"} 0.2
+	{test="three samples"} 0.4
+	{test="uneven samples"} 0.4
+	{test="NaN sample"} NaN
 
 # The histogram is ignored here so the result doesn't change but it has an info annotation now.
 eval_info instant at 1m quantile without(point)(0.8, {__name__=~"data(_histogram)?"})
 	{test="two samples"} 0.8
 	{test="three samples"} 1.6
 	{test="uneven samples"} 2.8
+	{test="NaN sample"} 0.6
 
 # The histogram is ignored here so there is no result but it has an info annotation now.
 eval_info instant at 1m quantile(0.8, data_histogram)
@@ -484,24 +499,27 @@ eval instant at 1m quantile without(point)(scalar(foo), data)
 	{test="two samples"} 0.8
 	{test="three samples"} 1.6
 	{test="uneven samples"} 2.8
-
+	{test="NaN sample"} 0.6
 
 eval instant at 1m quantile without(point)((scalar(foo)), data)
 	{test="two samples"} 0.8
 	{test="three samples"} 1.6
 	{test="uneven samples"} 2.8
+	{test="NaN sample"} 0.6
 
 eval instant at 1m quantile without(point)(NaN, data)
 	expect warn msg: PromQL warning: quantile value should be between 0 and 1, got NaN
-    {test="two samples"} NaN
-    {test="three samples"} NaN
-    {test="uneven samples"} NaN
+	{test="two samples"} NaN
+	{test="three samples"} NaN
+	{test="uneven samples"} NaN
+	{test="NaN sample"} NaN
 
 # Bug #15971.
 eval range from 0m to 1m step 10s quantile without(point) (scalar(foo), data)
 	{test="two samples"} 0 1 0 1 0 1 0.8
 	{test="three samples"} 0 2 0 2 0 2 1.6
 	{test="uneven samples"} 0 4 0 4 0 4 2.8
+	{test="NaN sample"} NaN 1 NaN 1 NaN 1 0.6
 
 # Tests for group.
 clear