diff --git a/sh/pre b/sh/pre
index 16c4079..bca3d62 100755
--- a/sh/pre
+++ b/sh/pre
@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 if [ -n "${ZSH_VERSION:-}" ]; then
-    $CC -dM -E - $=CPPFLAGS $=CFLAGS $=LDFLAGS < /dev/null
+    ${CC:-gcc} -dM -E - $=CPPFLAGS $=CFLAGS $=LDFLAGS < /dev/null
 else
-    $CC -dM -E - $CPPFLAGS $CFLAGS $LDFLAGS < /dev/null
+    ${CC:-gcc} -dM -E - $CPPFLAGS $CFLAGS $LDFLAGS < /dev/null
 fi