diff --git a/common/os_calls.c b/common/os_calls.c
index bb26d246..ee9792b1 100644
--- a/common/os_calls.c
+++ b/common/os_calls.c
@@ -1,7 +1,7 @@
 /**
  * xrdp: A Remote Desktop Protocol server.
  *
- * Copyright (C) Jay Sorg 2004-2013
+ * Copyright (C) Jay Sorg 2004-2014
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,11 @@
  * put all the os / arch define in here you want
  */
 
+/* To test for Windows (64 bit or 32 bit) use _WIN32 and _WIN64 in addition
+   for 64 bit windows.  _WIN32 is defined for both.
+   To test for Linux use __linux__.
+   To test for BSD use BSD */
+
 #if defined(HAVE_CONFIG_H)
 #include "config_ac.h"
 #endif
@@ -60,6 +65,13 @@
 #include <stdio.h>
 #include <locale.h>
 
+/* this is so we can use #ifdef BSD later */
+/* This is the recommended way of detecting BSD in the
+   FreeBSD Porter's Handbook. */
+#if (defined(__unix__) || defined(unix)) && !defined(USG)
+#include <sys/param.h>
+#endif
+
 #include "os_calls.h"
 #include "arch.h"
 #include "log.h"
@@ -596,9 +608,11 @@ g_tcp_local_socket(void)
 }
 
 /*****************************************************************************/
+/* returns error */
 int APP_CC
 g_sck_get_peer_cred(int sck, int *pid, int *uid, int *gid)
 {
+#if defined(SO_PEERCRED)
     int ucred_length;
     struct myucred
     {
@@ -625,6 +639,9 @@ g_sck_get_peer_cred(int sck, int *pid, int *uid, int *gid)
         *gid = credentials.gid;
     }
     return 0;
+#else
+    return 1;
+#endif
 }
 
 /*****************************************************************************/
@@ -3122,15 +3139,25 @@ g_text2bool(const char *s)
 }
 
 /*****************************************************************************/
+/* returns pointer or nil on error */
 void * APP_CC
 g_shmat(int shmid)
 {
-    return shmat(shmid, 0, 0);
+#if defined(_WIN32)
+    return 0;
+#else
+     return shmat(shmid, 0, 0);
+#endif
 }
 
 /*****************************************************************************/
+/* returns -1 on error */
 int APP_CC
 g_shmdt(const void *shmaddr)
 {
+#if defined(_WIN32)
+    return -1;
+#else
     return shmdt(shmaddr);
+#endif
 }