diff --git a/port/linux/test/pikaMain-test.cpp b/port/linux/test/pikaMain-test.cpp
index ce5ee1c6e..99b18faa0 100644
--- a/port/linux/test/pikaMain-test.cpp
+++ b/port/linux/test/pikaMain-test.cpp
@@ -1126,3 +1126,29 @@ TEST(pikaMain, class_def_print) {
     obj_deinit(self);
     EXPECT_EQ(pikaMemNow(), 0);
 }
+
+TEST(pikaMain, class_demo_1) {
+    /* init */
+    pikaMemInfo.heapUsedMax = 0;
+    /* run */
+    PikaObj* self = newRootObj((char*)"pikaMain", New_PikaMain);
+    __platform_printf((char*)"BEGIN\r\n");
+    obj_run(self, (char*)
+        "class MyClass:\n"
+        "    i = 12345\n"
+        "    def f(self):\n"
+        "        return 'hello world'\n"
+        "        \n"
+        "x = MyClass()\n"
+        " \n"
+        "print(x.i)\n"
+        "print(x.f())\n"
+    );
+    /* assert */
+    EXPECT_STREQ(log_buff[0], (char*)"hello world\r\n");
+    EXPECT_STREQ(log_buff[1], (char*)"12345\r\n");
+    EXPECT_STREQ(log_buff[2], (char*)"BEGIN\r\n");
+    /* deinit */
+    obj_deinit(self);
+    EXPECT_EQ(pikaMemNow(), 0);
+}
diff --git a/src/PikaParser.c b/src/PikaParser.c
index c15c1388b..cc37fde8e 100644
--- a/src/PikaParser.c
+++ b/src/PikaParser.c
@@ -1441,8 +1441,15 @@ char* AST_toPikaASM(AST* ast, Args* outBuffs) {
     if (strEqu(obj_getStr(ast, "block"), "class")) {
         Args* buffs = New_strBuff();
         char* declear = obj_getStr(ast, "declear");
-        char* thisClass = strsGetFirstToken(buffs, declear, '(');
-        char* superClass = strsCut(buffs, declear, '(', ')');
+        char* thisClass = NULL;
+        char* superClass = NULL;
+        if (strIsContain(declear, '(')) {
+            thisClass = strsGetFirstToken(buffs, declear, '(');
+            superClass = strsCut(buffs, declear, '(', ')');
+        } else {
+            thisClass = declear;
+            superClass = "";
+        }
         if (strEqu("", superClass)) {
             /* default superClass */
             superClass = "PikaStdLib.PikaObj";