diff --git a/src/obj.h b/src/obj.h
index 9227d44a..e70df6d8 100644
--- a/src/obj.h
+++ b/src/obj.h
@@ -103,7 +103,7 @@ struct Py_ : PyObject {
     inline static const char* _mod() { return #mod; } \
     inline static const char* _name() { return #name; }
 
-#define PY_BUILTIN_CLASS(name) inline static PyVar _type(VM* vm) { return vm->tp_##name; }
+// #define PY_BUILTIN_CLASS(name) inline static PyVar _type(VM* vm) { return vm->tp_##name; }
 
 static thread_local emhash8::HashMap<void*, std::vector<int*>> _obj_pool;
 
diff --git a/src/pocketpy.h b/src/pocketpy.h
index dfbd4953..ba30d98f 100644
--- a/src/pocketpy.h
+++ b/src/pocketpy.h
@@ -578,8 +578,8 @@ void add_module_math(VM* vm){
     vm->bind_func<1>(mod, "isnan", CPP_LAMBDA(vm->PyBool(std::isnan(vm->num_to_float(args[0])))));
     vm->bind_func<1>(mod, "isinf", CPP_LAMBDA(vm->PyBool(std::isinf(vm->num_to_float(args[0])))));
     vm->bind_func<1>(mod, "fabs", CPP_LAMBDA(vm->PyFloat(std::fabs(vm->num_to_float(args[0])))));
-    vm->bind_func<1>(mod, "floor", CPP_LAMBDA(vm->PyInt(std::floor(vm->num_to_float(args[0])))));
-    vm->bind_func<1>(mod, "ceil", CPP_LAMBDA(vm->PyInt(std::ceil(vm->num_to_float(args[0])))));
+    vm->bind_func<1>(mod, "floor", CPP_LAMBDA(vm->PyInt((i64)std::floor(vm->num_to_float(args[0])))));
+    vm->bind_func<1>(mod, "ceil", CPP_LAMBDA(vm->PyInt((i64)std::ceil(vm->num_to_float(args[0])))));
     vm->bind_func<1>(mod, "sqrt", CPP_LAMBDA(vm->PyFloat(std::sqrt(vm->num_to_float(args[0])))));
 }
 
@@ -671,7 +671,7 @@ void add_module_re(VM* vm){
 
 void add_module_random(VM* vm){
     PyVar mod = vm->new_module("random");
-    std::srand(std::time(nullptr));
+    std::srand(std::time(0));
     vm->bind_func<1>(mod, "seed", [](VM* vm, const pkpy::Args& args) {
         std::srand((unsigned int)vm->PyInt_AS_C(args[0]));
         return vm->None;
diff --git a/src/vm.h b/src/vm.h
index bc301a97..ec94fdc3 100644
--- a/src/vm.h
+++ b/src/vm.h
@@ -943,7 +943,8 @@ public:
     }
 
     inline void check_type(const PyVar& obj, const PyVar& type){
-        if(!obj->is_type(type)) TypeError("expected " + OBJ_NAME(type).escape(true) + ", but got " + OBJ_TP_NAME(obj).escape(true));
+        if(obj->is_type(type)) return;
+        TypeError("expected " + OBJ_NAME(type).escape(true) + ", but got " + OBJ_TP_NAME(obj).escape(true));
     }
 
     template<typename T>