diff --git a/cmd/promtool/main.go b/cmd/promtool/main.go
index 7de7996642..e1074549e3 100644
--- a/cmd/promtool/main.go
+++ b/cmd/promtool/main.go
@@ -71,12 +71,12 @@ func main() {
 	queryCmdFmt := queryCmd.Flag("format", "Output format of the query.").Short('o').Default("promql").Enum("promql", "json")
 
 	queryInstantCmd := queryCmd.Command("instant", "Run instant query.")
-	queryInstantServer := queryInstantCmd.Arg("server", "Prometheus server to query.").Required().String()
+	queryInstantServer := queryInstantCmd.Arg("server", "Prometheus server to query.").Required().URL()
 	queryInstantExpr := queryInstantCmd.Arg("expr", "PromQL query expression.").Required().String()
 	queryInstantTime := queryInstantCmd.Flag("time", "Query evaluation time (RFC3339 or Unix timestamp).").String()
 
 	queryRangeCmd := queryCmd.Command("range", "Run range query.")
-	queryRangeServer := queryRangeCmd.Arg("server", "Prometheus server to query.").Required().String()
+	queryRangeServer := queryRangeCmd.Arg("server", "Prometheus server to query.").Required().URL()
 	queryRangeExpr := queryRangeCmd.Arg("expr", "PromQL query expression.").Required().String()
 	queryRangeHeaders := queryRangeCmd.Flag("header", "Extra headers to send to server.").StringMap()
 	queryRangeBegin := queryRangeCmd.Flag("start", "Query range start time (RFC3339 or Unix timestamp).").String()
@@ -437,9 +437,12 @@ func CheckMetrics() int {
 }
 
 // QueryInstant performs an instant query against a Prometheus server.
-func QueryInstant(url, query, evalTime string, p printer) int {
+func QueryInstant(url *url.URL, query, evalTime string, p printer) int {
+	if url.Scheme == "" {
+		url.Scheme = "http"
+	}
 	config := api.Config{
-		Address: url,
+		Address: url.String(),
 	}
 
 	// Create new client.
@@ -475,9 +478,12 @@ func QueryInstant(url, query, evalTime string, p printer) int {
 }
 
 // QueryRange performs a range query against a Prometheus server.
-func QueryRange(url string, headers map[string]string, query, start, end string, step time.Duration, p printer) int {
+func QueryRange(url *url.URL, headers map[string]string, query, start, end string, step time.Duration, p printer) int {
+	if url.Scheme == "" {
+		url.Scheme = "http"
+	}
 	config := api.Config{
-		Address: url,
+		Address: url.String(),
 	}
 
 	if len(headers) > 0 {
@@ -547,6 +553,9 @@ func QueryRange(url string, headers map[string]string, query, start, end string,
 
 // QuerySeries queries for a series against a Prometheus server.
 func QuerySeries(url *url.URL, matchers []string, start, end string, p printer) int {
+	if url.Scheme == "" {
+		url.Scheme = "http"
+	}
 	config := api.Config{
 		Address: url.String(),
 	}
@@ -581,6 +590,9 @@ func QuerySeries(url *url.URL, matchers []string, start, end string, p printer)
 
 // QueryLabels queries for label values against a Prometheus server.
 func QueryLabels(url *url.URL, name string, start, end string, p printer) int {
+	if url.Scheme == "" {
+		url.Scheme = "http"
+	}
 	config := api.Config{
 		Address: url.String(),
 	}
diff --git a/cmd/promtool/main_test.go b/cmd/promtool/main_test.go
index f3f6d0e162..112c387c93 100644
--- a/cmd/promtool/main_test.go
+++ b/cmd/promtool/main_test.go
@@ -17,6 +17,7 @@ import (
 	"fmt"
 	"net/http"
 	"net/http/httptest"
+	"net/url"
 	"testing"
 	"time"
 
@@ -27,15 +28,18 @@ func TestQueryRange(t *testing.T) {
 	s, getRequest := mockServer(200, `{"status": "success", "data": {"resultType": "matrix", "result": []}}`)
 	defer s.Close()
 
+	urlObject, err := url.Parse(s.URL)
+	require.Equal(t, nil, err)
+
 	p := &promqlPrinter{}
-	exitCode := QueryRange(s.URL, map[string]string{}, "up", "0", "300", 0, p)
+	exitCode := QueryRange(urlObject, map[string]string{}, "up", "0", "300", 0, p)
 	require.Equal(t, "/api/v1/query_range", getRequest().URL.Path)
 	form := getRequest().Form
 	require.Equal(t, "up", form.Get("query"))
 	require.Equal(t, "1", form.Get("step"))
 	require.Equal(t, 0, exitCode)
 
-	exitCode = QueryRange(s.URL, map[string]string{}, "up", "0", "300", 10*time.Millisecond, p)
+	exitCode = QueryRange(urlObject, map[string]string{}, "up", "0", "300", 10*time.Millisecond, p)
 	require.Equal(t, "/api/v1/query_range", getRequest().URL.Path)
 	form = getRequest().Form
 	require.Equal(t, "up", form.Get("query"))
@@ -47,8 +51,11 @@ func TestQueryInstant(t *testing.T) {
 	s, getRequest := mockServer(200, `{"status": "success", "data": {"resultType": "vector", "result": []}}`)
 	defer s.Close()
 
+	urlObject, err := url.Parse(s.URL)
+	require.Equal(t, nil, err)
+
 	p := &promqlPrinter{}
-	exitCode := QueryInstant(s.URL, "up", "300", p)
+	exitCode := QueryInstant(urlObject, "up", "300", p)
 	require.Equal(t, "/api/v1/query", getRequest().URL.Path)
 	form := getRequest().Form
 	require.Equal(t, "up", form.Get("query"))