diff --git a/src/compiler.h b/src/compiler.h
index 394e5cd3..3957def1 100644
--- a/src/compiler.h
+++ b/src/compiler.h
@@ -395,7 +395,7 @@ private:
         }
         func.code = make_sp<CodeObject>(parser->src, func.name.str());
         this->codes.push(func.code);
-        co()->_rvalue += 1; EXPR_TUPLE(); co()->_rvalue -= 1;
+        co()->_rvalue += 1; EXPR(); co()->_rvalue -= 1;
         emit(OP_RETURN_VALUE);
         func.code->optimize(vm);
         this->codes.pop();
diff --git a/src/vm.h b/src/vm.h
index 0692f3cd..f0e3f6e9 100644
--- a/src/vm.h
+++ b/src/vm.h
@@ -450,7 +450,7 @@ template<> bool _py_cast<bool>(VM* vm, const PyVar& obj){
     return obj == vm->True;
 }
 
-PyVar py_var(VM* vm, const char* val){
+PyVar py_var(VM* vm, const char val[]){
     return VAR(Str(val));
 }
 
diff --git a/tests/_bugs.py b/tests/_bugs.py
new file mode 100644
index 00000000..d6b53bb9
--- /dev/null
+++ b/tests/_bugs.py
@@ -0,0 +1,4 @@
+# https://github.com/blueloveTH/pocketpy/issues/37
+
+mp = map(lambda x:  x**2, [1, 2, 3, 4, 5]  )
+assert list(mp) == [1, 4, 9, 16, 25]
\ No newline at end of file