diff --git a/promql/promql_test.go b/promql/promql_test.go
index 38dafb61ca..18704fb6b0 100644
--- a/promql/promql_test.go
+++ b/promql/promql_test.go
@@ -34,3 +34,18 @@ func TestEvaluations(t *testing.T) {
 		})
 	}
 }
+
+func TestOne(t *testing.T) {
+	files, err := filepath.Glob("testdata/nan.test")
+	require.NoError(t, err)
+
+	for _, fn := range files {
+		t.Run(fn, func(t *testing.T) {
+			test, err := newTestFromFile(t, fn)
+			require.NoError(t, err)
+			require.NoError(t, test.Run())
+
+			test.Close()
+		})
+	}
+}
diff --git a/promql/quantile.go b/promql/quantile.go
index e2de98840c..f4a6fa6a13 100644
--- a/promql/quantile.go
+++ b/promql/quantile.go
@@ -71,6 +71,9 @@ type metricWithBuckets struct {
 //
 // If q>1, +Inf is returned.
 func bucketQuantile(q float64, buckets buckets) float64 {
+	if math.IsNaN(q){
+		return math.NaN()
+	}
 	if q < 0 {
 		return math.Inf(-1)
 	}
@@ -181,11 +184,11 @@ func ensureMonotonic(buckets buckets) {
 // quantile calculates the given quantile of a vector of samples.
 //
 // The Vector will be sorted.
-// If 'values' has zero elements, NaN is returned.
+// If 'values' has zero elements or 'q' == NaN, NaN is returned.
 // If q<0, -Inf is returned.
 // If q>1, +Inf is returned.
 func quantile(q float64, values vectorByValueHeap) float64 {
-	if len(values) == 0 {
+	if len(values) == 0 || q == math.NaN() {
 		return math.NaN()
 	}
 	if q < 0 {
diff --git a/promql/testdata/nan.test b/promql/testdata/nan.test
new file mode 100644
index 0000000000..a9583ac9a9
--- /dev/null
+++ b/promql/testdata/nan.test
@@ -0,0 +1,21 @@
+# Two histograms with 4 buckets each (x_sum and x_count not included,
+# only buckets). Lowest bucket for one histogram < 0, for the other >
+# 0. They have the same name, just separated by label. Not useful in
+# practice, but can happen (if clients change bucketing), and the
+# server has to cope with it.
+
+# Test histogram.
+load 5m
+	testhistogram_bucket{le="0.1", start="positive"}	0+5x10
+	testhistogram_bucket{le=".2", start="positive"}		0+7x10
+	testhistogram_bucket{le="1e0", start="positive"}	0+11x10
+	testhistogram_bucket{le="+Inf", start="positive"}	0+12x10
+	testhistogram_bucket{le="-.2", start="negative"}	0+1x10
+	testhistogram_bucket{le="-0.1", start="negative"}	0+2x10
+	testhistogram_bucket{le="0.3", start="negative"}	0+2x10
+	testhistogram_bucket{le="+Inf", start="negative"}	0+3x10
+
+
+# Quantile value in lowest bucket, which is positive.
+eval instant at 50m histogram_quantile(NaN, testhistogram_bucket{start="positive"})
+	{start="positive"} 0