diff --git a/kerl b/kerl
index de357b0..56852c3 100755
--- a/kerl
+++ b/kerl
@@ -292,7 +292,7 @@ do_build()
         Darwin)
             if [ `gcc --version | grep llvm | wc -l` = "1" ]; then
                 if lion_support $1; then
-                    true
+                    KERL_CONFIGURE_OPTIONS="CFLAGS=-O0 $KERL_CONFIGURE_OPTIONS"
                 else
                     if [ -x "`which gcc-4.2`" ]; then
                         KERL_CONFIGURE_OPTIONS="CC=gcc-4.2 $KERL_CONFIGURE_OPTIONS"