diff --git a/codegen/templates/transform_2d.pyx b/codegen/templates/transform_2d.pyx
index bfc1499..c487fb9 100644
--- a/codegen/templates/transform_2d.pyx
+++ b/codegen/templates/transform_2d.pyx
@@ -246,12 +246,15 @@ cdef class Transform2D:
         return t
 
     def __imatmul__(self, Transform2D other) -> Transform2D:
-        self.xx = other.tdotx(self.xx, self.xy)
-        self.xy = other.tdoty(self.xx, self.xy)
-        self.yx = other.tdotx(self.yx, self.yy)
-        self.yy = other.tdoty(self.yx, self.yy)
-        self.ox = other.mulx(self.ox, self.oy)
-        self.oy = other.muly(self.ox, self.oy)
+        cdef py_float xx = other.tdotx(self.xx, self.xy)
+        cdef py_float xy = other.tdoty(self.xx, self.xy)
+        cdef py_float yx = other.tdotx(self.yx, self.yy)
+        cdef py_float yy = other.tdoty(self.yx, self.yy)
+        cdef py_float ox = other.mulx(self.ox, self.oy)
+        cdef py_float oy = other.muly(self.ox, self.oy)
+        self.xx, self.xy = xx, xy
+        self.yx, self.yy = yx, yy
+        self.ox, self.oy = ox, oy
         return self
 
     cdef inline py_float _determinant(self) noexcept:
@@ -343,7 +346,7 @@ cdef class Transform2D:
         return t
 
     def rotate_ip(self, py_float rotation, /) -> Transform2D:
-        self.__imul__(Transform2D.rotation(rotation))
+        self.__imatmul__(Transform2D.rotation(rotation))
         return self
 
     def rotated(self, py_float rotation, /) -> Transform2D:
diff --git a/codegen/templates/transform_3d.pyx b/codegen/templates/transform_3d.pyx
index f8002a2..0d0c4fa 100644
--- a/codegen/templates/transform_3d.pyx
+++ b/codegen/templates/transform_3d.pyx
@@ -367,18 +367,22 @@ cdef class Transform3D:
         return t
 
     def __imatmul__(self, Transform3D other) -> Transform3D:
-        self.xx = other.tdotx(self.xx, self.xy, self.xz)
-        self.xy = other.tdoty(self.xx, self.xy, self.xz)
-        self.xz = other.tdotz(self.xx, self.xy, self.xz)
-        self.yx = other.tdotx(self.yx, self.yy, self.yz)
-        self.yy = other.tdoty(self.yx, self.yy, self.yz)
-        self.yz = other.tdotz(self.yx, self.yy, self.yz)
-        self.zx = other.tdotx(self.zx, self.zy, self.zz)
-        self.zy = other.tdoty(self.zx, self.zy, self.zz)
-        self.zz = other.tdotz(self.zx, self.zy, self.zz)
-        self.ox = other.mulx(self.ox, self.oy, self.oz)
-        self.oy = other.muly(self.ox, self.oy, self.oz)
-        self.oz = other.mulz(self.ox, self.oy, self.oz)
+        cdef py_float xx = other.tdotx(self.xx, self.xy, self.xz)
+        cdef py_float xy = other.tdoty(self.xx, self.xy, self.xz)
+        cdef py_float xz = other.tdotz(self.xx, self.xy, self.xz)
+        cdef py_float yx = other.tdotx(self.yx, self.yy, self.yz)
+        cdef py_float yy = other.tdoty(self.yx, self.yy, self.yz)
+        cdef py_float yz = other.tdotz(self.yx, self.yy, self.yz)
+        cdef py_float zx = other.tdotx(self.zx, self.zy, self.zz)
+        cdef py_float zy = other.tdoty(self.zx, self.zy, self.zz)
+        cdef py_float zz = other.tdotz(self.zx, self.zy, self.zz)
+        cdef py_float ox = other.mulx(self.ox, self.oy, self.oz)
+        cdef py_float oy = other.muly(self.ox, self.oy, self.oz)
+        cdef py_float oz = other.mulz(self.ox, self.oy, self.oz)
+        self.xx, self.xy, self.xz = xx, xy, xz
+        self.yx, self.yy, self.yz = yx, yy, yz
+        self.zx, self.zy, self.zz = zx, zy, zz
+        self.ox, self.oy, self.oz = ox, oy, oz
         return self
 
     cdef inline py_float _determinant(self) noexcept:
@@ -424,7 +428,7 @@ cdef class Transform3D:
         return t
 
     def rotate_ip(self, Vec3 axis, py_float angle, /) -> Transform3D:
-        self.__imul__(Transform3D.rotating(axis, angle))
+        self.__imatmul__(Transform3D.rotating(axis, angle))
         return self
 
     def rotated(self, Vec3 axis, py_float angle, /) -> Transform3D:
diff --git a/pyproject.toml b/pyproject.toml
index 7bd712e..54e4d11 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ requires = ["setuptools", "cython"]
 
 [project]
 name = "gdmath"
-version = "1.4.1"
+version = "1.4.2"
 description = "GdMath: a fast math library for game development"
 readme = "README.md"
 requires-python = ">= 3.9"
diff --git a/tests/test_transform_2d.py b/tests/test_transform_2d.py
index 9a27e91..87e4a11 100644
--- a/tests/test_transform_2d.py
+++ b/tests/test_transform_2d.py
@@ -71,6 +71,13 @@ def test_matmul():
     assert (t1 @ t2).is_close(ans)
     assert t1(t2).is_close(ans)
 
+def test_imatmul():
+    t1 = Transform2D(1, 2, 3, 4, 5, 6)
+    t2 = Transform2D(3, 1, 2, 6, 5, 4)
+    t3 = Transform2D(t1)
+    t3 @= t2
+    assert t2 @ t1 == t3
+
 def test_determinant():
     assert isclose(Transform2D(1.6, 2.5, 3.4, 4.3, 5.2, 6.1).determinant, -1.62)
 
diff --git a/tests/test_transform_3d.py b/tests/test_transform_3d.py
index 5daefb6..057cb5d 100644
--- a/tests/test_transform_3d.py
+++ b/tests/test_transform_3d.py
@@ -70,6 +70,13 @@ def test_matmul():
     assert (t1 @ t2).is_close(ans)
     assert t1(t2).is_close(ans)
 
+def test_imatmul():
+    t1 = Transform3D(*range(1, 13))
+    t2 = Transform3D(10, 8, 4, 6, 12, 7, 5, 3, 2, 1, 11, 9)
+    t3 = Transform3D(t1)
+    t3 @= t2
+    assert t2 @ t1 == t3
+
 def test_determinant():
     assert isclose(Transform3D(1.12, 2.11, 0, 0, 5.8, 6.7, 7.6, 8.5, 0, 1, 2, 3).determinant, 43.6572)