diff --git a/Mac/mwerks/mwerks_plugin_config.h b/Mac/mwerks/mwerks_plugin_config.h
index c087b827682..0052df80be7 100644
--- a/Mac/mwerks/mwerks_plugin_config.h
+++ b/Mac/mwerks/mwerks_plugin_config.h
@@ -5,6 +5,6 @@
 #define USE_GUSI		/* Stdio implemented with GUSI */
 #define USE_MSL			/* Use MSL libraries */
 #ifdef USE_MSL
-#define USE_PRECOMPILED_HEADERS 0	/* Don't use precomp headers: we include our own */
+#define MSL_USE_PRECOMPILED_HEADERS 0	/* Don't use precomp headers: we include our own */
 #include <ansi_prefix.mac.h>
 #endif