diff --git a/include/wx/defs.h b/include/wx/defs.h
index 32c27378fc..15e3598434 100644
--- a/include/wx/defs.h
+++ b/include/wx/defs.h
@@ -26,9 +26,7 @@
     defined(__hpux) || defined(sun) || defined(__SUN__) || defined(_AIX) || \
     defined(__EMX__)
 
-    #ifndef __UNIX__
-        #define __UNIX__
-    #endif // Unix
+    #define __UNIX_LIKE__
 
     // Helps SGI compilation, apparently
     #ifdef __SGI__
@@ -190,6 +188,12 @@
 #undef PACKAGE
 #undef VERSION
 
+// if we're on a Unixsystem but didn't use configure (so that setup.h didn't
+// define __UNIX__), do define __UNIX__ now
+#if !defined(__UNIX__) && defined(__UNIX_LIKE__)
+    #define __UNIX__
+#endif // Unix
+
 #include "wx/version.h"
 
 // ============================================================================