diff --git a/python/taichi/lang/ast/ast_transformer.py b/python/taichi/lang/ast/ast_transformer.py
index 79a2bb8cf7297..ef405ce94582a 100644
--- a/python/taichi/lang/ast/ast_transformer.py
+++ b/python/taichi/lang/ast/ast_transformer.py
@@ -1011,28 +1011,19 @@ def build_Compare(ctx, node):
         ops_static = {
             ast.In: lambda l, r: l in r,
             ast.NotIn: lambda l, r: l not in r,
-            ast.Is: lambda l, r: l is r,
-            ast.IsNot: lambda l, r: l is not r,
         }
         if ctx.is_in_static_scope():
             ops = {**ops, **ops_static}
         operands = [node.left.ptr] + [comparator.ptr for comparator in node.comparators]
         val = True
         for i, node_op in enumerate(node.ops):
+            if isinstance(node_op, (ast.Is, ast.IsNot)):
+                name = "is" if isinstance(node_op, ast.Is) else "is not"
+                raise TaichiSyntaxError(f'Operator "{name}" in Taichi scope is not supported.')
             l = operands[i]
             r = operands[i + 1]
             op = ops.get(type(node_op))
-            if isinstance(node_op, (ast.Is, ast.IsNot)):
-                name = "is" if isinstance(node_op, ast.Is) else "is not"
-                warnings.warn_explicit(
-                    f'Operator "{name}" in Taichi scope is deprecated, '
-                    f"and it will be removed in Taichi v1.6.0. "
-                    f"Please avoid using it.",
-                    DeprecationWarning,
-                    ctx.file,
-                    node.lineno + ctx.lineno_offset,
-                    module="taichi",
-                )
+
             if op is None:
                 if type(node_op) in ops_static:
                     raise TaichiSyntaxError(f'"{type(node_op).__name__}" is only supported inside `ti.static`.')
diff --git a/tests/python/test_ast_refactor.py b/tests/python/test_ast_refactor.py
index 669c419dd724a..deab2b0310c44 100644
--- a/tests/python/test_ast_refactor.py
+++ b/tests/python/test_ast_refactor.py
@@ -164,17 +164,6 @@ def foo(a: ti.template()):
         assert a[i] == b[i]
 
 
-@test_utils.test()
-def test_compare_fail():
-    with pytest.raises(ti.TaichiCompilationError, match='"Is" is only supported inside `ti.static`.'):
-
-        @ti.kernel
-        def foo():
-            None is None
-
-        foo()
-
-
 @test_utils.test()
 def test_single_compare():
     @ti.kernel
diff --git a/tests/python/test_compare.py b/tests/python/test_compare.py
index 487e88c70f7ee..84a335bc4c054 100644
--- a/tests/python/test_compare.py
+++ b/tests/python/test_compare.py
@@ -171,33 +171,6 @@ def foo(a: ti.template()) -> ti.i32:
         foo(ti.i32)
 
 
-@test_utils.test()
-def test_static_is():
-    @ti.kernel
-    def is_f32(tp: ti.template()) -> ti.i32:
-        return ti.static(tp is ti.f32)
-
-    @ti.kernel
-    def is_not_f32(tp: ti.template()) -> ti.i32:
-        return ti.static(tp is not ti.f32)
-
-    assert is_f32(ti.f32) == 1
-    assert is_f32(ti.i32) == 0
-    assert is_not_f32(ti.f32) == 0
-    assert is_not_f32(ti.i32) == 1
-
-
-@test_utils.test()
-def test_non_static_is():
-    with pytest.raises(ti.TaichiCompilationError, match='"Is" is only supported inside `ti.static`.'):
-
-        @ti.kernel
-        def is_f32(tp: ti.template()) -> ti.i32:
-            return tp is ti.f32
-
-        is_f32(ti.f32)
-
-
 @test_utils.test(default_ip=ti.i64, require=ti.extension.data64)
 def test_compare_ret_type():
     # The purpose of this test is to make sure a comparison returns i32
diff --git a/tests/python/test_deprecation.py b/tests/python/test_deprecation.py
index f1feeaa4f54aa..a46ea7ca2b798 100644
--- a/tests/python/test_deprecation.py
+++ b/tests/python/test_deprecation.py
@@ -69,11 +69,8 @@ def test_deprecate_rwtexture_ndim():
 
 
 @test_utils.test()
-def test_deprecate_is_is_not():
-    with pytest.warns(
-        DeprecationWarning,
-        match='Operator "is" in Taichi scope is deprecated, ' "and it will be removed in Taichi v1.6.0.",
-    ):
+def test_remove_is_is_not():
+    with pytest.raises(ti.TaichiSyntaxError, match='Operator "is" in Taichi scope is not supported'):
 
         @ti.kernel
         def func():