diff --git a/CHANGELOG.md b/CHANGELOG.md
index a0f9a4e9..b2d5a269 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # Changelog
 
+## [4.3.1] 2024-08-24
+
+### Added
+ - Added support for "is not" type test
+
 ## [4.3.0] 2024-08-18
 
 ### Added
diff --git a/gdtoolkit/parser/gdscript.lark b/gdtoolkit/parser/gdscript.lark
index 401fb571..b06bc3d3 100644
--- a/gdtoolkit/parser/gdscript.lark
+++ b/gdtoolkit/parser/gdscript.lark
@@ -223,9 +223,9 @@ not_in_op: "not" "in"
 !?pow_expr: type_test ("**" asless_type_test)*
           | actual_type_cast ("**" asless_type_test)+
 !?asless_pow_expr: asless_type_test ("**" asless_type_test)*
-!?type_test: await_expr ("is" TYPE_HINT)*
-           | actual_type_cast ("is" TYPE_HINT)+
-!?asless_type_test: await_expr ("is" TYPE_HINT)*
+!?type_test: await_expr (("is" | "is not") TYPE_HINT)*
+           | actual_type_cast (("is" | "is not") TYPE_HINT)+
+!?asless_type_test: await_expr (("is" | "is not") TYPE_HINT)*
 !?await_expr: ("await")* call_expr
 ?call_expr: attr_expr
           | (NAME | GET | SET) _call_arglist -> standalone_call
diff --git a/tests/formatter/input-output-pairs/type_test_expressions.in.gd b/tests/formatter/input-output-pairs/type_test_expressions.in.gd
index 647f167c..0de02ddd 100644
--- a/tests/formatter/input-output-pairs/type_test_expressions.in.gd
+++ b/tests/formatter/input-output-pairs/type_test_expressions.in.gd
@@ -3,3 +3,5 @@ class X:
 		var x = 1 is int is bool
 		var y = 1 is int is bool is bool is bool is bool is bool is bool is bool is bool is bool is bool is bool is bool is bool
 		print([1,2.1] is Array[int])
+		var z = 1 is not int
+		var z1 = 1 is not int is not bool is not bool is not bool is not bool is not bool is not bool is not bool is not bool is not bool
diff --git a/tests/formatter/input-output-pairs/type_test_expressions.out.gd b/tests/formatter/input-output-pairs/type_test_expressions.out.gd
index 42ebc54b..5f0056f5 100644
--- a/tests/formatter/input-output-pairs/type_test_expressions.out.gd
+++ b/tests/formatter/input-output-pairs/type_test_expressions.out.gd
@@ -19,3 +19,17 @@ class X:
 			is bool
 		)
 		print([1, 2.1] is Array[int])
+		var z = 1 is not int
+		var z1 = (
+			1
+			is not int
+			is not bool
+			is not bool
+			is not bool
+			is not bool
+			is not bool
+			is not bool
+			is not bool
+			is not bool
+			is not bool
+		)
diff --git a/tests/valid-gd-scripts/expressions.gd b/tests/valid-gd-scripts/expressions.gd
index 530117eb..b2e47d11 100644
--- a/tests/valid-gd-scripts/expressions.gd
+++ b/tests/valid-gd-scripts/expressions.gd
@@ -44,6 +44,7 @@ func foo():
 	~8
 	5 ** 5
 	x is int
+	x is not int
 	x is Xyz # TODO: fix/remove x.Type
 	x is Zyx.Qwe # TODO: fix/remove x.Type
 	x.attr