diff --git a/CHANGELOG b/CHANGELOG
index 1c69a313..8113c4f7 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -6,6 +6,10 @@ HISTORY
 
  ++ New features:
 
+  2011-06-26: Simon Goldschmidt (patch by Cameron Gutman)
+  * tcp.c, tcp_out.c: bug #33604: added some more asserts to check that
+    pcb->state != LISTEN
+
    2011-05-14: Simon Goldschmidt (patch by Stéphane Lesage)
   * tcpip.c/.h: patch #7449 allow tcpip callback from interrupt with static
     memory message
diff --git a/src/core/mem.c b/src/core/mem.c
index 98375553..9dbbaf65 100644
--- a/src/core/mem.c
+++ b/src/core/mem.c
@@ -190,7 +190,9 @@ static struct mem *ram_end;
 static struct mem *lfree;
 
 /** concurrent access protection */
+#if !NO_SYS
 static sys_mutex_t mem_mutex;
+#endif
 
 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT