diff --git a/zutil.h b/zutil.h
index 902a304cc..06e09c2de 100644
--- a/zutil.h
+++ b/zutil.h
@@ -137,15 +137,11 @@ extern z_const char * const z_errmsg[10]; /* indexed by 2-zlib_error */
 #  endif
 #endif
 
-#if defined(MACOS) || defined(TARGET_OS_MAC)
+#if TARGET_OS_OSX
 #  define OS_CODE  7
 #  ifndef Z_SOLO
 #    if defined(__MWERKS__) && __dest_os != __be_os && __dest_os != __win32_os
 #      include <unix.h> /* for fdopen */
-#    else
-#      ifndef fdopen
-#        define fdopen(fd,mode) NULL /* No fdopen() */
-#      endif
 #    endif
 #  endif
 #endif