diff --git a/tools/cc.py b/tools/cc.py
index 989344c..9f9ec4f 100644
--- a/tools/cc.py
+++ b/tools/cc.py
@@ -892,7 +892,7 @@ class CcInterp(lark.visitors.Interpreter):
         s = self._lookup_symbol(ident)
         assert s is not None, f'unknown identifier {ident}'
         if isinstance(s, FunctionSpec) or ident in self.global_scope.symbols:
-            reg = reg or self._get_reg()
+            reg = self.cur_fun.regs.take(reg=reg, orwhatever=True)
             return SetAddr(self.cur_fun, [reg, ident])
         else:
             if s.type.volatile: