diff -ur orig/openttd-1.3.2/src/os/macosx/osx_stdafx.h openttd-1.3.2/src/os/macosx/osx_stdafx.h
--- orig/openttd-1.3.2/src/os/macosx/osx_stdafx.h	2013-07-27 17:09:32.000000000 +0200
+++ openttd-1.3.2/src/os/macosx/osx_stdafx.h	2013-08-09 22:34:03.000000000 +0200
@@ -78,8 +78,10 @@
 #endif /* NSInteger */
 
 /* OS X SDK versions >= 10.5 have a non-const iconv. */
-#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5
-#	define HAVE_NON_CONST_ICONV
+#ifdef MAC_OS_X_VERSION_10_5
+#	if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5
+#		define HAVE_NON_CONST_ICONV
+#	endif
 #endif
 
 #endif /* MACOS_STDAFX_H */