diff --git a/port/linux/.vscode/launch.json b/port/linux/.vscode/launch.json
index 731de052d..3a92acf72 100644
--- a/port/linux/.vscode/launch.json
+++ b/port/linux/.vscode/launch.json
@@ -18,9 +18,10 @@
                 // "--gtest_filter=packtool.packread"
                 // "--gtest_filter=thread.test1"
                 // "--gtest_filter=eventloop.test1"
-                "--gtest_filter=parser.tuple_single"
+                // "--gtest_filter=parser.tuple_single"
                 // "--gtest_filter=parser.*"
                 // "--gtest_filter=parser.page_add"
+                "--gtest_filter=builtin.fn_default1"
             ],
             "stopAtEntry": false,
             "cwd": "${workspaceFolder}",
diff --git a/src/PikaVM.c b/src/PikaVM.c
index 53bccce63..53f40d3e9 100644
--- a/src/PikaVM.c
+++ b/src/PikaVM.c
@@ -1124,51 +1124,52 @@ Arg* obj_runMethodArg(PikaObj* self,
 }
 
 static char* _kw_pos_to_default_all(FunctionArgsInfo* f,
-                                    char* arg_name,
+                                    char* sArgName,
                                     int* argc,
                                     Arg* argv[],
-                                    Arg* call_arg) {
+                                    Arg* aCall) {
 #if PIKA_NANO_ENABLE
     return arg_name;
 #endif
-    int n_default_skip = 0;
-    int n_default_skiped = 0;
+    int iDefaultSkip = 0;
+    int iDefaultSkiped = 0;
     if (f->i_arg == f->n_arg) {
-        n_default_skip = f->n_default - f->n_arg;
+        iDefaultSkip = f->n_default - f->n_arg + f->n_positional;
     }
-    while (strIsContain(arg_name, '=')) {
-        strPopLastToken(arg_name, '=');
-        Arg* kw_arg = NULL;
+    while (strIsContain(sArgName, '=')) {
+        strPopLastToken(sArgName, '=');
+        Arg* aKeyword = NULL;
         /* load default arg from kws */
         if (f->kw != NULL) {
-            kw_arg = pikaDict_getArg(f->kw, arg_name);
-            if (kw_arg != NULL) {
-                Arg* arg_new = arg_copy(kw_arg);
-                argv[(*argc)++] = arg_new;
-                pikaDict_removeArg(f->kw, kw_arg);
+            aKeyword = pikaDict_getArg(f->kw, sArgName);
+            if (aKeyword != NULL) {
+                Arg* aNew = arg_copy(aKeyword);
+                argv[(*argc)++] = aNew;
+                pikaDict_removeArg(f->kw, aKeyword);
+                goto __next;
             }
         }
-        if (f->kw == NULL || kw_arg == NULL) {
-            /* can not load defalut from kw */
-            if (NULL != call_arg && f->is_default) {
-                /* load pos to default with right order */
-                if (n_default_skiped < n_default_skip) {
-                    n_default_skiped++;
-                    arg_name = strPopLastToken(f->type_list, ',');
-                    continue;
-                }
-                /* load default from pos */
-                if (f->i_arg > f->n_positional) {
-                    arg_setNameHash(call_arg,
-                                    hash_time33EndWith(arg_name, ':'));
-                    argv[(*argc)++] = call_arg;
-                    return (char*)1;
-                }
+
+        /* load default arg from pos */
+        if (NULL != aCall && f->is_default) {
+            /* load pos to default with right order */
+            if (iDefaultSkiped < iDefaultSkip) {
+                iDefaultSkiped++;
+                sArgName = strPopLastToken(f->type_list, ',');
+                continue;
+            }
+            /* load default from pos */
+            if (f->i_arg > f->n_positional) {
+                arg_setNameHash(aCall, hash_time33EndWith(sArgName, ':'));
+                argv[(*argc)++] = aCall;
+                return (char*)1;
             }
         }
-        arg_name = strPopLastToken(f->type_list, ',');
+
+    __next:
+        sArgName = strPopLastToken(f->type_list, ',');
     }
-    return arg_name;
+    return sArgName;
 }
 
 static int _kw_to_pos_one(FunctionArgsInfo* f,
diff --git a/test/builtin-test.cpp b/test/builtin-test.cpp
index 3520a69d7..d4078e34d 100644
--- a/test/builtin-test.cpp
+++ b/test/builtin-test.cpp
@@ -188,9 +188,14 @@ TEST(builtin, int_extern) {
     EXPECT_EQ(pikaMemNow(), 0);
 }
 
-TEST_RUN_SINGLE_FILE_PASS(builtin, list_tuple_equ, "test/python/builtin/list_tuple_equ.py")
+TEST_RUN_SINGLE_FILE_PASS(builtin,
+                          list_tuple_equ,
+                          "test/python/builtin/list_tuple_equ.py")
+
+TEST_RUN_SINGLE_FILE_PASS(builtin,
+                          fn_default1,
+                          "test/python/builtin/fn_default1.py")
 
 #endif
 
-
 TEST_END
\ No newline at end of file
diff --git a/test/python/builtin/fn_default1.py b/test/python/builtin/fn_default1.py
new file mode 100644
index 000000000..c325cfd54
--- /dev/null
+++ b/test/python/builtin/fn_default1.py
@@ -0,0 +1,45 @@
+
+class Test:
+    def test_default(self,
+                     dev: str,
+                     baudrate=115200,
+                     bytesize=8,
+                     parity='N',
+                     stopbits=1,
+                     xonxoff=0
+                     ):
+        return dev, baudrate, bytesize, parity, stopbits, xonxoff
+
+
+def test_default(
+    dev: str,
+    baudrate=115200,
+    bytesize=8,
+    parity='N',
+    stopbits=1,
+    xonxoff=0
+):
+    return dev, baudrate, bytesize, parity, stopbits, xonxoff
+
+
+dev, baudrate, bytesize, parity, stopbits, xonxoff = test_default(
+    'uart3', 9600)
+
+assert dev == 'uart3'
+assert baudrate == 9600
+assert bytesize == 8
+assert parity == 'N'
+assert stopbits == 1
+assert xonxoff == 0
+
+test = Test()
+dev, baudrate, bytesize, parity, stopbits, xonxoff = test.test_default(
+    'uart3', 9600)
+
+assert dev == 'uart3'
+assert baudrate == 9600
+assert bytesize == 8
+assert parity == 'N'
+assert stopbits == 1
+assert xonxoff == 0
+print('PASS')