diff --git a/src/context/context.go b/src/context/context.go
index da294b1292..5184b94e51 100644
--- a/src/context/context.go
+++ b/src/context/context.go
@@ -428,6 +428,9 @@ func WithTimeout(parent Context, timeout time.Duration) (Context, CancelFunc) {
 //
 // The provided key must be comparable.
 func WithValue(parent Context, key, val interface{}) Context {
+	if key == nil {
+		panic("nil key")
+	}
 	if !reflect.TypeOf(key).Comparable() {
 		panic("key is not comparable")
 	}
diff --git a/src/context/context_test.go b/src/context/context_test.go
index aa26161d2b..99456b188d 100644
--- a/src/context/context_test.go
+++ b/src/context/context_test.go
@@ -583,6 +583,10 @@ func TestWithValueChecksKey(t *testing.T) {
 	if panicVal == nil {
 		t.Error("expected panic")
 	}
+	panicVal = recoveredValue(func() { WithValue(Background(), nil, "bar") })
+	if got, want := fmt.Sprint(panicVal), "nil key"; got != want {
+		t.Errorf("panic = %q; want %q", got, want)
+	}
 }
 
 func recoveredValue(fn func()) (v interface{}) {