diff --git a/tests/check/elements/qtmux.c b/tests/check/elements/qtmux.c
index 45e31c0e67..e367634709 100644
--- a/tests/check/elements/qtmux.c
+++ b/tests/check/elements/qtmux.c
@@ -208,6 +208,7 @@ check_qtmux_pad (GstStaticPadTemplate * srctemplate, const gchar * sinkname,
   fail_unless (gst_pad_push_event (mysrcpad, gst_event_new_segment (&segment)));
 
   inbuffer = gst_buffer_new_and_alloc (1);
+  gst_buffer_memset (inbuffer, 0, 0, 1);
   caps = gst_pad_get_pad_template_caps (mysrcpad);
   gst_pad_set_caps (mysrcpad, caps);
   gst_caps_unref (caps);
@@ -296,6 +297,7 @@ check_qtmux_pad_fragmented (GstStaticPadTemplate * srctemplate,
   fail_unless (gst_pad_push_event (mysrcpad, gst_event_new_segment (&segment)));
 
   inbuffer = gst_buffer_new_and_alloc (1);
+  gst_buffer_memset (inbuffer, 0, 0, 1);
   caps = gst_pad_get_pad_template_caps (mysrcpad);
   gst_pad_set_caps (mysrcpad, caps);
   gst_caps_unref (caps);
@@ -526,6 +528,7 @@ GST_START_TEST (test_reuse)
 
   inbuffer = gst_buffer_new_and_alloc (1);
   fail_unless (inbuffer != NULL);
+  gst_buffer_memset (inbuffer, 0, 0, 1);
   caps = gst_pad_get_pad_template_caps (mysrcpad);
   gst_pad_set_caps (mysrcpad, caps);
   gst_caps_unref (caps);
@@ -817,6 +820,7 @@ test_average_bitrate_custom (const gchar * elementname,
 
   for (i = 0; i < 3; i++) {
     inbuffer = gst_buffer_new_and_alloc (bytes[i]);
+    gst_buffer_memset (inbuffer, 0, 0, bytes[i]);
     caps = gst_pad_get_pad_template_caps (mysrcpad);
     gst_pad_set_caps (mysrcpad, caps);
     gst_caps_unref (caps);