diff --git a/src/cmd/tools/dtest/docker/harness/query_api_test.go b/src/cmd/tools/dtest/docker/harness/query_api_test.go
index e7ab6ff4b0..dd389afd66 100644
--- a/src/cmd/tools/dtest/docker/harness/query_api_test.go
+++ b/src/cmd/tools/dtest/docker/harness/query_api_test.go
@@ -36,26 +36,22 @@ type urlTest struct {
 }
 
 func TestInvalidInstantQueryReturns400(t *testing.T) {
-	coord := singleDBNodeDockerResources.Coordinator()
+	urlPrefixes := []string{"", "prometheus/", "m3query/"}
 
-	instantQueryBadRequestTest := []urlTest{
+	urlTests := addPrefixes(urlPrefixes, []urlTest{
 		{"missing query", queryURL("query", "")},
 		{"invalid query", queryURL("query", "@!")},
 		{"invalid time", queryURL("time", "INVALID")},
 		{"invalid timeout", queryURL("timeout", "INVALID")},
-	}
+	})
 
-	for _, tt := range instantQueryBadRequestTest {
-		t.Run(tt.name, func(t *testing.T) {
-			assert.NoError(t, coord.RunQuery(verifyStatus(400), tt.url), "for query '%v'", tt.url)
-		})
-	}
+	testInvalidQueryReturns400(t, urlTests)
 }
 
 func TestInvalidRangeQueryReturns400(t *testing.T) {
-	coord := singleDBNodeDockerResources.Coordinator()
+	urlPrefixes := []string{"", "prometheus/", "m3query/"}
 
-	queryBadRequestTest := []urlTest{
+	urlTests := addPrefixes(urlPrefixes, []urlTest{
 		{"missing query", queryRangeURL("query", "")},
 		{"invalid query", queryRangeURL("query", "@!")},
 		{"missing start", queryRangeURL("start", "")},
@@ -65,15 +61,34 @@ func TestInvalidRangeQueryReturns400(t *testing.T) {
 		{"missing step", queryRangeURL("step", "")},
 		{"invalid step", queryRangeURL("step", "INVALID")},
 		{"invalid timeout", queryRangeURL("timeout", "INVALID")},
-	}
+	})
 
-	for _, tt := range queryBadRequestTest {
+	testInvalidQueryReturns400(t, urlTests)
+}
+
+func testInvalidQueryReturns400(t *testing.T, tests []urlTest) {
+	coord := singleDBNodeDockerResources.Coordinator()
+
+	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			assert.NoError(t, coord.RunQuery(verifyStatus(400), tt.url), "for query '%v'", tt.url)
 		})
 	}
 }
 
+func addPrefixes(prefixes []string, tests []urlTest) []urlTest {
+	res := make([]urlTest, 0)
+	for _, prefix := range prefixes {
+		for _, t := range tests {
+			res = append(res, urlTest{
+				fmt.Sprintf("%v %v", prefix, t.name),
+				fmt.Sprintf("%v%v", prefix, t.url),
+			})
+		}
+	}
+	return res
+}
+
 func queryURL(key, value string) string {
 	params := map[string]string{
 		"query": "foo",
diff --git a/src/query/api/v1/handler/prometheus/native/read_common.go b/src/query/api/v1/handler/prometheus/native/read_common.go
index f86ba1a304..b2c1760125 100644
--- a/src/query/api/v1/handler/prometheus/native/read_common.go
+++ b/src/query/api/v1/handler/prometheus/native/read_common.go
@@ -176,7 +176,7 @@ func read(
 	parseOpts := engine.Options().ParseOptions()
 	parser, err := promql.Parse(params.Query, params.Step, tagOpts, parseOpts)
 	if err != nil {
-		return emptyResult, err
+		return emptyResult, xerrors.NewInvalidParamsError(err)
 	}
 
 	// Detect clients closing connections.