diff --git a/src/sem/SymbolTable.cpp b/src/sem/SymbolTable.cpp
index dee0284..280fc8c 100644
--- a/src/sem/SymbolTable.cpp
+++ b/src/sem/SymbolTable.cpp
@@ -300,4 +300,14 @@ void SymbolTable::registerBuiltinFunctions() {
     starttime.scope_level = 0;
     starttime.is_builtin = true;
     addSymbol(starttime);
+
+    // stoptime: void stoptime()
+    Symbol stoptime;
+    stoptime.name = "stoptime";
+    stoptime.kind = SymbolKind::Function;
+    stoptime.type = ir::Type::GetFunctionType(ir::Type::GetVoidType(), {});  // 无参数，返回 void
+    stoptime.param_types = {};
+    stoptime.scope_level = 0;
+    stoptime.is_builtin = true;
+    addSymbol(stoptime);
 }
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