diff --git a/Source/TcpPort.m b/Source/TcpPort.m
index 1c29f1cf8..0253dcde6 100644
--- a/Source/TcpPort.m
+++ b/Source/TcpPort.m
@@ -44,12 +44,15 @@
 #include <sys/param.h>		/* for MAXHOSTNAMELEN */
 #include <arpa/inet.h>		/* for inet_ntoa() */
 #include <string.h>		/* for memset() */
-
 #ifndef WIN32
 #include <sys/time.h>
 #include <sys/resource.h>
 #endif
 
+/* On some systems FD_ZERO is a macro that uses bzero().
+   Just define it to use GCC's builtin memset(). */
+#define bzero(PTR, LEN) memset (PTR, 0, LEN)
+
 static int debug_tcp_port = 0;