diff --git a/port/linux/.vscode/launch.json b/port/linux/.vscode/launch.json
index a21e3a9c4..7c76975e4 100644
--- a/port/linux/.vscode/launch.json
+++ b/port/linux/.vscode/launch.json
@@ -20,7 +20,7 @@
                 // "--gtest_filter=eventloop.test1"
                 // "--gtest_filter=parser.tuple_single"
                 // "--gtest_filter=parser.*"
-                "--gtest_filter=parser.default_tuple"
+                "--gtest_filter=VM.is"
             ],
             "stopAtEntry": false,
             "cwd": "${workspaceFolder}",
diff --git a/src/PikaParser.c b/src/PikaParser.c
index d17d79f18..7168caa47 100644
--- a/src/PikaParser.c
+++ b/src/PikaParser.c
@@ -1591,32 +1591,36 @@ static void _AST_parse_slice(AST* ast, Args* buffs, char* stmt) {
     }
 }
 
-char* Suger_not_in(Args* out_buffs, char* line) {
-#if PIKA_NANO_ENABLE
-    return line;
-#endif
+#include <string.h>
+#include "pikaScript.h"
+
+char* _Suger_process(Args* out_buffs,
+                     char* line,
+                     char* token1,
+                     char* token2,
+                     char* format) {
     char* ret = line;
     char* stmt1 = "";
     char* stmt2 = "";
-    PIKA_BOOL got_not_in = PIKA_FALSE;
+    PIKA_BOOL got_tokens = PIKA_FALSE;
     PIKA_BOOL skip = PIKA_FALSE;
     Args buffs = {0};
-    if (1 != Cursor_count(line, TOKEN_operator, " not ")) {
+
+    if (1 != Cursor_count(line, TOKEN_operator, token1)) {
         ret = line;
         goto __exit;
     }
-    if (1 != Cursor_count(line, TOKEN_operator, " in ")) {
+    if (1 != Cursor_count(line, TOKEN_operator, token2)) {
         ret = line;
         goto __exit;
     }
 
-    /* stmt1 not in stmt2 => not stmt1 in stmt2 */
     Cursor_forEach(cs, line) {
         Cursor_iterStart(&cs);
-        if (!got_not_in) {
-            if (strEqu(cs.token1.pyload, " not ") &&
-                strEqu(cs.token2.pyload, " in ")) {
-                got_not_in = PIKA_TRUE;
+        if (!got_tokens) {
+            if (strEqu(cs.token1.pyload, token1) &&
+                strEqu(cs.token2.pyload, token2)) {
+                got_tokens = PIKA_TRUE;
                 Cursor_iterEnd(&cs);
                 continue;
             }
@@ -1632,18 +1636,29 @@ char* Suger_not_in(Args* out_buffs, char* line) {
         Cursor_iterEnd(&cs);
     }
     Cursor_deinit(&cs);
-    if (!got_not_in) {
+
+    if (!got_tokens) {
         ret = line;
         goto __exit;
     }
-    ret = strsFormat(out_buffs, strGetSize(line) + 3, " not %s in %s", stmt1,
-                     stmt2);
-    goto __exit;
+
+    ret = strsFormat(out_buffs,
+                     strGetSize(line) + strlen(token1) + strlen(token2), format,
+                     stmt1, stmt2);
+
 __exit:
     strsDeinit(&buffs);
     return ret;
 }
 
+char* Suger_not_in(Args* out_buffs, char* line) {
+    return _Suger_process(out_buffs, line, " not ", " in ", " not %s in %s");
+}
+
+char* Suger_is_not(Args* out_buffs, char* line) {
+    return _Suger_process(out_buffs, line, " is ", " not ", " not %s is %s");
+}
+
 AST* AST_parseStmt(AST* ast, char* stmt) {
     Args buffs = {0};
     char* assignment = Cursor_splitCollect(&buffs, stmt, "(", 0);
@@ -1713,6 +1728,7 @@ AST* AST_parseStmt(AST* ast, char* stmt) {
     /* solve operator stmt */
     if (STMT_operator == stmtType) {
         right = Suger_not_in(&buffs, right);
+        right = Suger_is_not(&buffs, right);
         char* rightWithoutSubStmt = _remove_sub_stmt(&buffs, right);
         char* operator= Lexer_getOperator(&buffs, rightWithoutSubStmt);
         if (NULL == operator) {
diff --git a/src/PikaVM.c b/src/PikaVM.c
index 1fd74c9cc..6d8a4180f 100644
--- a/src/PikaVM.c
+++ b/src/PikaVM.c
@@ -2826,6 +2826,11 @@ static Arg* VM_instruction_handler_OPT(PikaObj* self,
             }
             goto exit;
         }
+        if ((op.t1 != op.t2) && (op.t1 != ARG_TYPE_NONE) &&
+            (op.t2 != ARG_TYPE_NONE)) {
+            op.res = arg_setInt(op.res, "", 0);
+            goto exit;
+        }
 #endif
         op.opt = "==";
         _OPT_EQU(&op);
diff --git a/test/VM-test.cpp b/test/VM-test.cpp
index 8701f10d3..a3ddeffff 100644
--- a/test/VM-test.cpp
+++ b/test/VM-test.cpp
@@ -2848,6 +2848,8 @@ TEST_RUN_SINGLE_FILE_PASS(datastruct,
 TEST_RUN_LINES_EXCEPT_OUTPUT(vm, single_tuple, "(1,)", "(1,)\r\n")
 TEST_RUN_LINES_EXCEPT_OUTPUT(vm, single_tuple_str, "('test',)", "('test',)\r\n")
 
+TEST_RUN_SINGLE_FILE_PASS(vm, is_not, "test/python/builtin/is_not.py")
+
 #endif
 
 TEST_END
\ No newline at end of file
diff --git a/test/parse-test.cpp b/test/parse-test.cpp
index c1d2be18a..ce692e307 100644
--- a/test/parse-test.cpp
+++ b/test/parse-test.cpp
@@ -5614,6 +5614,15 @@ TEST_LINES2ASM(default_tuple,
                "0 RET \n"
                "B0\n")
 
+TEST_LINES2ASM(is_not,
+               "A is not None",
+               "B0\n"
+               "2 REF A\n"
+               "2 REF None\n"
+               "1 OPT  is \n"
+               "0 OPT  not \n"
+               "B0\n")
+
 #endif
 
 TEST_END
\ No newline at end of file
diff --git a/test/python/builtin/is_not.py b/test/python/builtin/is_not.py
new file mode 100644
index 000000000..f6ee818cc
--- /dev/null
+++ b/test/python/builtin/is_not.py
@@ -0,0 +1,10 @@
+
+assert (1 is not 1) == False
+assert (1 is not 2) == True
+assert (1 is not None) == True
+assert (None is not None) == False
+assert (None is not 1) == True
+assert (1 is not 1.0) == True
+assert (1.0 is not 1) == True
+assert (1.0 is not 1.0) == False
+print("PASS")