diff --git a/gio/goutputstream.c b/gio/goutputstream.c
index 0f5b9d9ee..c59eb67e0 100644
--- a/gio/goutputstream.c
+++ b/gio/goutputstream.c
@@ -384,7 +384,7 @@ g_output_stream_vprintf (GOutputStream  *stream,
   gboolean  success;
 
   g_return_val_if_fail (G_IS_OUTPUT_STREAM (stream), FALSE);
-  g_return_val_if_fail (cancellable == NULL || G_IS_CANCELLABLE (stream), FALSE);
+  g_return_val_if_fail (cancellable == NULL || G_IS_CANCELLABLE (cancellable), FALSE);
   g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
   g_return_val_if_fail (format != NULL, FALSE);