diff --git a/src/lisp/Config.x86_darwin b/src/lisp/Config.x86_darwin
index 404521fb6ea0d209226cfc7f46ab8f02c89616e2..e1daf4f0077660796997e8a07b1a795423599754 100644
--- a/src/lisp/Config.x86_darwin
+++ b/src/lisp/Config.x86_darwin
@@ -2,6 +2,12 @@
 
 include Config.x86_common
 
+# Use gcc-4.2 on Darwin in case someone has Xcode 4 installed.
+# Currently there are bugs in cmucl that cause errors when using gcc
+# from Xcode 4.  Xcode 3 (for OSX 10.5 and 10.6) has gcc-4.2, so this
+# shouldn't be a problem.
+CC = gcc-4.2
+
 # Compile code that will run on OSX 10.4 (Tiger)
 MIN_VER = -mmacosx-version-min=10.4