diff --git a/sys/imperx/gstframelinksrc.c b/sys/imperx/gstframelinksrc.c
index ec8b1df..9c8eee8 100644
--- a/sys/imperx/gstframelinksrc.c
+++ b/sys/imperx/gstframelinksrc.c
@@ -154,7 +154,7 @@ gst_framelinksrc_class_init (GstFramelinkSrcClass * klass)
 static void
 gst_framelinksrc_reset (GstFramelinkSrc * src)
 {
-  g_assert_null (src->grabber);
+  g_assert (src->grabber == NULL);
 
   src->acq_started = FALSE;