Index: uspace/drv/uhci/callback.c
===================================================================
--- uspace/drv/uhci/callback.c	(revision 113aef89b94c7f1a18abf64bb1301664eba1c90f)
+++ uspace/drv/uhci/callback.c	(revision d956aa5d8b7561e08f70e86ec2d8f8d130b976cf)
@@ -37,6 +37,7 @@
 
 	/* update the old buffer */
-	if (instance->new_buffer) {
-		memcpy(instance->new_buffer, instance->old_buffer, instance->buffer_size);
+	if (instance->new_buffer &&
+	  (instance->new_buffer != instance->old_buffer)) {
+		memcpy(instance->old_buffer, instance->new_buffer, instance->buffer_size);
 		free32(instance->new_buffer);
 		instance->new_buffer = NULL;