diff --git a/core/net/mac/mac.c b/core/net/mac/mac.c
index 199c6a389..b207744cb 100644
--- a/core/net/mac/mac.c
+++ b/core/net/mac/mac.c
@@ -28,32 +28,38 @@
  *
  * This file is part of the Contiki operating system.
  *
- * $Id: mac.c,v 1.1 2010/02/18 21:48:39 adamdunkels Exp $
+ * $Id: mac.c,v 1.2 2010/02/23 18:49:58 adamdunkels Exp $
  */
 
 #include "net/mac/mac.h"
 
+#define DEBUG 0
+#if DEBUG
 #include <stdio.h>
+#define PRINTF(...) printf(__VA_ARGS__)
+#else /* DEBUG */
+#define PRINTF(...)
+#endif /* DEBUG */
 
 /*---------------------------------------------------------------------------*/
 void
 mac_call_sent_callback(mac_callback_t sent, void *ptr, int status, int num_tx)
 {
-  /*  printf("mac_callback_t %p ptr %p status %d num_tx %d\n",
-      sent, ptr, status, num_tx);*/
-  /*  switch(status) {
+  PRINTF("mac_callback_t %p ptr %p status %d num_tx %d\n",
+         sent, ptr, status, num_tx);
+  switch(status) {
   case MAC_TX_COLLISION:
-    printf("mac: collision after %d tx\n", num_tx);
+    PRINTF("mac: collision after %d tx\n", num_tx);
     break; 
   case MAC_TX_NOACK:
-    printf("mac: noack after %d tx\n", num_tx);
+    PRINTF("mac: noack after %d tx\n", num_tx);
     break;
   case MAC_TX_OK:
-    printf("mac: sent after %d tx\n", num_tx);
+    PRINTF("mac: sent after %d tx\n", num_tx);
     break;
   default:
-    printf("mac: error %d after %d tx\n", status, num_tx);
-    }*/
+    PRINTF("mac: error %d after %d tx\n", status, num_tx);
+  }
 
   if(sent) {
     sent(ptr, status, num_tx);