diff --git a/src/ASTPrinter.cpp b/src/ASTPrinter.cpp
index 60d78af..1b05d6c 100644
--- a/src/ASTPrinter.cpp
+++ b/src/ASTPrinter.cpp
@@ -90,7 +90,10 @@ std::any ASTPrinter::visitFuncDef(SysYParser::FuncDefContext *ctx){
   cout << getIndent() << ctx->funcType()->getText() << ' ' << ctx->Ident()->getText();
   cout << ctx->LPAREN()->getText();
   if (ctx->funcFParams()) ctx->funcFParams()->accept(this);
-  cout << ctx->RPAREN()->getText();
+  if(ctx->RPAREN())
+    cout << ctx->RPAREN()->getText();
+  else 
+    cout << "<missing \')\'?>";
   ctx->blockStmt()->accept(this);
   return nullptr;
 }