diff --git a/modules/libreg/include/NSReg.h b/modules/libreg/include/NSReg.h
index be832f75268..c0cba20da7d 100644
--- a/modules/libreg/include/NSReg.h
+++ b/modules/libreg/include/NSReg.h
@@ -100,16 +100,15 @@ typedef struct _reginfo
 #define UNIX_GLOBAL_FLAG     "MOZILLA_SHARED_REGISTRY"
 
 /* Platform-dependent declspec for library interface */
-#if defined(XP_PC)
+#if defined(XP_PC) && !defined(XP_OS2_EMX)
   #if defined(WIN32)
-
     #if defined (STANDALONE_REGISTRY)
        #define VR_INTERFACE(type)     __declspec(dllexport) type __cdecl
     #else
        #define VR_INTERFACE(type)     __declspec(dllexport) type __stdcall
     #endif
 
-  #elif defined(XP_OS2)
+  #elif defined(XP_OS2_VACPP)
   #define VR_INTERFACE(type)     type _Optlink
   #else
   #define VR_INTERFACE(type)     type _far _pascal _export
diff --git a/modules/libreg/src/VerReg.c b/modules/libreg/src/VerReg.c
index 29eb1d363fb..fc4e7028a3a 100644
--- a/modules/libreg/src/VerReg.c
+++ b/modules/libreg/src/VerReg.c
@@ -43,6 +43,11 @@
 #include <io.h>
 #endif
 
+#if defined(XP_OS2)
+#include <sys/types.h>
+#include <sys/stat.h>
+#endif
+
 #include <stdio.h>
 #include <string.h>
 
diff --git a/modules/libreg/src/reg.c b/modules/libreg/src/reg.c
index a75be9ef4ac..c6ff1aaa0f5 100644
--- a/modules/libreg/src/reg.c
+++ b/modules/libreg/src/reg.c
@@ -74,7 +74,7 @@
 #include "reg.h"
 #include "NSReg.h"
 
-#if defined(XP_UNIX)
+#if defined(XP_UNIX) || defined(XP_OS2)
 #ifndef MAX_PATH
 #define MAX_PATH 1024
 #endif
diff --git a/modules/libreg/src/vr_stubs.c b/modules/libreg/src/vr_stubs.c
index d39f9d5a54c..439181985fc 100644
--- a/modules/libreg/src/vr_stubs.c
+++ b/modules/libreg/src/vr_stubs.c
@@ -127,7 +127,7 @@ char* vr_findVerRegName()
  *  WINDOWS STUBS
  * ------------------------------------------------------------------
  */
-#ifdef XP_PC
+#if defined(XP_PC) && !defined(XP_OS2)
 #include "windows.h"
 #define PATHLEN 260
 
diff --git a/modules/libreg/src/vr_stubs.h b/modules/libreg/src/vr_stubs.h
index 29c1b8eb968..37f9a9b5fe3 100644
--- a/modules/libreg/src/vr_stubs.h
+++ b/modules/libreg/src/vr_stubs.h
@@ -50,12 +50,15 @@
 #ifdef XP_MAC
 #include <stat.h>
 #else
-#if defined(BSDI) && !defined(BSDI_2)
+#if ( defined(BSDI) && !defined(BSDI_2) ) || defined(XP_OS2_EMX)
 #include <sys/types.h>
 #endif
 #include <sys/stat.h>
 #endif
 
+#ifdef XP_OS2_VACPP
+#include <direct.h>
+#endif
 
 #ifndef FALSE
 #define FALSE 0
@@ -213,7 +216,6 @@ typedef PRFileDesc* XP_File;
 
 #endif /*STANDALONE_REGISTRY*/
 
-
 /*--- file open modes for stdio ---*/
 #ifdef USE_STDIO_MODES
 #define XP_FILE_READ             "r"
@@ -240,7 +242,6 @@ typedef PRFileDesc* XP_File;
 #define XP_FILE_WRITE_BIN        PR_WRONLY, 0644
 #define XP_FILE_UPDATE           (PR_RDWR|PR_CREATE_FILE), 0644
 #define XP_FILE_TRUNCATE         (PR_RDWR | PR_TRUNCATE), 0644
-
 #define XP_FILE_UPDATE_BIN       PR_RDWR|PR_CREATE_FILE, 0644
 #define XP_FILE_TRUNCATE_BIN     (PR_RDWR | PR_TRUNCATE), 0644