diff --git a/rpython/rtyper/lltypesystem/ll2ctypes.py b/rpython/rtyper/lltypesystem/ll2ctypes.py
index 33853fc..5cf48c1 100644
--- a/rpython/rtyper/lltypesystem/ll2ctypes.py
+++ b/rpython/rtyper/lltypesystem/ll2ctypes.py
@@ -1181,7 +1181,7 @@ if sys.platform == 'darwin':
         expr = r'[^\(\)\s]*lib%s\.[^\(\)\s]*' % re.escape(name)
         fdout, ccout = tempfile.mkstemp()
         os.close(fdout)
-        cmd = 'if type gcc >/dev/null 2>&1; then CC=gcc; else CC=cc; fi;' \
+        cmd = 'if type gcc >/dev/null 2>&1; then : ${CC:=gcc}; else : ${CC:=cc}; fi;' \
               '$CC -Wl,-t -o ' + ccout + ' 2>&1 -l' + name
         try:
             f = os.popen(cmd)