diff --git a/configure.in b/configure.in
index ef25fc23ca..9130131f6b 100644
--- a/configure.in
+++ b/configure.in
@@ -290,6 +290,7 @@ case "${host}" in
   *-pc-os2_emx | *-pc-os2-emx )
     AC_DEFINE(__EMX__)
     USE_OS2=1
+    AC_DEFINE(__OS2__)
     PROGRAM_EXT=".exe"
     DEFAULT_DEFAULT_wxUSE_PM=1
     dnl "c++" wrapper is not always available, so always use plain gcc.
diff --git a/setup.h.in b/setup.h.in
index a2ad505a07..3d02255d6f 100644
--- a/setup.h.in
+++ b/setup.h.in
@@ -125,6 +125,9 @@
 #undef WINVER
 #endif
 
+/* OS/2 with EMX */
+#undef __OS2__
+
 /* enable native status bar under Win32 */
 #if defined(__WIN95__) && !defined(__WXUNIVERSAL__)
 #define wxUSE_NATIVE_STATUSBAR 1