diff --git a/src/modules/Image/layer_channel.h b/src/modules/Image/layer_channel.h
index 75f6a008912aaff58ecbdfb889d974d46360268e..4c76ad86de8e8a11a594781fb847fbfcc4d372de 100644
--- a/src/modules/Image/layer_channel.h
+++ b/src/modules/Image/layer_channel.h
@@ -2,7 +2,7 @@
 || This file is part of Pike. For copyright information see COPYRIGHT.
 || Pike is distributed under GPL, LGPL and MPL. See the file COPYING
 || for more information.
-|| $Id: layer_channel.h,v 1.9 2008/01/15 21:51:07 grubba Exp $
+|| $Id: layer_channel.h,v 1.10 2008/07/11 13:11:39 mast Exp $
 */
 
 /* template for operator layer row function */
@@ -11,12 +11,14 @@ static void LM_FUNC(rgb_group *s,rgb_group *l,rgb_group *d,
 		    rgb_group *sa,rgb_group *la,rgb_group *da,
 		    int len,double alpha)
 {
-   MEMCPY(da,sa,sizeof(rgb_group)*len); /* always copy alpha channel */
+  if (da != sa)
+    MEMCPY(da,sa,sizeof(rgb_group)*len); /* always copy alpha channel */
 #define da da da /* protect */
    if (alpha==0.0)
    {
 #ifdef LAYER_DUAL
-      MEMCPY(d,s,sizeof(rgb_group)*len);
+     if (d != s)
+       MEMCPY(d,s,sizeof(rgb_group)*len);
 #endif
       return; 
    }