diff --git a/core/net/mac/cxmac.c b/core/net/mac/cxmac.c
index ea3fcb070..4fec40d60 100644
--- a/core/net/mac/cxmac.c
+++ b/core/net/mac/cxmac.c
@@ -28,7 +28,6 @@
  *
  * This file is part of the Contiki operating system.
  *
- * $Id: cxmac.c,v 1.15 2010/10/03 20:37:32 adamdunkels Exp $
  */
 
 /**
@@ -421,7 +420,7 @@ send_packet(void)
   uint8_t strobe[MAX_STROBE_SIZE];
   int strobe_len, len;
   int is_broadcast = 0;
-  int is_reliable;
+/*int is_reliable;*/
   struct encounter *e;
   struct queuebuf *packet;
   int is_already_streaming = 0;
@@ -450,8 +449,8 @@ send_packet(void)
            packetbuf_addr(PACKETBUF_ADDR_RECEIVER)->u8[1]);
 #endif /* UIP_CONF_IPV6 */
   }
-  is_reliable = packetbuf_attr(PACKETBUF_ATTR_RELIABLE) ||
-    packetbuf_attr(PACKETBUF_ATTR_ERELIABLE);
+/* is_reliable = packetbuf_attr(PACKETBUF_ATTR_RELIABLE) ||
+    packetbuf_attr(PACKETBUF_ATTR_ERELIABLE);*/
   len = NETSTACK_FRAMER.create();
   strobe_len = len + sizeof(struct cxmac_hdr);
   if(len < 0 || strobe_len > (int)sizeof(strobe)) {
diff --git a/core/net/mac/xmac.c b/core/net/mac/xmac.c
index 64d21c4a3..041685280 100644
--- a/core/net/mac/xmac.c
+++ b/core/net/mac/xmac.c
@@ -28,7 +28,6 @@
  *
  * This file is part of the Contiki operating system.
  *
- * $Id: xmac.c,v 1.60 2011/01/25 14:31:09 adamdunkels Exp $
  */
 
 /**
@@ -463,7 +462,7 @@ send_packet(void)
   uint8_t strobe[MAX_STROBE_SIZE];
   int strobe_len, len;
   int is_broadcast = 0;
-  int is_reliable;
+/*int is_reliable; */
   struct encounter *e;
   struct queuebuf *packet;
   int is_already_streaming = 0;
@@ -491,8 +490,8 @@ send_packet(void)
            packetbuf_addr(PACKETBUF_ADDR_RECEIVER)->u8[1]);
 #endif /* UIP_CONF_IPV6 */
   }
-  is_reliable = packetbuf_attr(PACKETBUF_ATTR_RELIABLE) ||
-    packetbuf_attr(PACKETBUF_ATTR_ERELIABLE);
+/*  is_reliable = packetbuf_attr(PACKETBUF_ATTR_RELIABLE) ||
+    packetbuf_attr(PACKETBUF_ATTR_ERELIABLE); */
 
   packetbuf_set_attr(PACKETBUF_ATTR_MAC_ACK, 1);
   len = NETSTACK_FRAMER.create();
diff --git a/core/net/rime/collect.c b/core/net/rime/collect.c
index f51ba3a54..a73059cac 100644
--- a/core/net/rime/collect.c
+++ b/core/net/rime/collect.c
@@ -33,7 +33,6 @@
  *
  * This file is part of the Contiki operating system.
  *
- * $Id: collect.c,v 1.73 2011/01/18 16:05:53 adamdunkels Exp $
  */
 
 /**
@@ -126,7 +125,7 @@ struct ack_msg {
    full, incoming packets are dropped instead of being forwarded. */
 #define MAX_MAC_REXMITS            2
 #define MAX_ACK_MAC_REXMITS        5
-#define REXMIT_TIME                CLOCK_SECOND * 32 / NETSTACK_RDC_CHANNEL_CHECK_RATE
+#define REXMIT_TIME                (CLOCK_SECOND * 32 / NETSTACK_RDC_CHANNEL_CHECK_RATE)
 #define FORWARD_PACKET_LIFETIME_BASE    REXMIT_TIME * 2
 #define MAX_SENDING_QUEUE          3 * QUEUEBUF_NUM / 4
 #define MIN_AVAILABLE_QUEUE_ENTRIES 4
diff --git a/core/sys/pt.h b/core/sys/pt.h
index 3f1467c62..9433a1086 100644
--- a/core/sys/pt.h
+++ b/core/sys/pt.h
@@ -30,7 +30,6 @@
  *
  * Author: Adam Dunkels <adam@sics.se>
  *
- * $Id: pt.h,v 1.3 2008/10/14 12:46:39 nvt-se Exp $
  */
 
 /**
@@ -112,7 +111,7 @@ struct pt {
  *
  * \hideinitializer
  */
-#define PT_BEGIN(pt) { char PT_YIELD_FLAG = 1; LC_RESUME((pt)->lc)
+#define PT_BEGIN(pt) { char PT_YIELD_FLAG = 1; if (PT_YIELD_FLAG) {;} LC_RESUME((pt)->lc)
 
 /**
  * Declare the end of a protothread.