diff --git a/bitmask/bitmask.py b/bitmask/bitmask.py
index e95a7da..dcf34bc 100644
--- a/bitmask/bitmask.py
+++ b/bitmask/bitmask.py
@@ -158,13 +158,6 @@ class Bitmask:
         """Alias the + operator in reverse."""
         return self.__add__(other)
 
-    def __iadd__(self, other):
-        """Implement += operator.
-
-        Aliased to `Bitmask.__add__`.
-        """
-        return self + other
-
     def __or__(self, other):
         """Implement | operator."""
         return self + other
@@ -173,13 +166,6 @@ class Bitmask:
         """Alias the | operator in reverse."""
         return self.__or__(other)
 
-    def __ior__(self, other):
-        """Implement |= operator.
-
-        Aliased to `Bitmask.__add__`.
-        """
-        return self | other
-
     def __xor__(self, other):
         """Implement ^ operator."""
         return self.__mask_op(other, lambda a, b : a ^ b)
@@ -188,13 +174,6 @@ class Bitmask:
         """Alias the ^ operator in reverse."""
         return self.__xor__(other)
 
-    def __ixor(self, other):
-        """Implement ^= operator.
-
-        Aliased to `Bitmask.__xor__`.
-        """
-        return self ^ other
-
     def __and__(self, other):
         """AND bitmasks/flags together."""
         return self.__mask_op(other, lambda a, b : a & b)
@@ -203,25 +182,10 @@ class Bitmask:
         """Alias the & operator in reverse."""
         return self.__and__(other)
 
-    def __iand(self, other):
-        """AND bitmasks/flags together.
-
-        Aliased to `Bitmask.__and__`.
-        """
-        return self & other
-
     def __sub__(self, other):
         """Subtract by bitmask/flag."""
         return self.__mask_op(other, lambda a, b : a & ~b)
 
-    def __isub__(self, other):
-        """Subtract a bitmask/flag.
-
-        Aliased to `Bitmask.__sub__`.
-        """
-        self = self - other
-        return self
-
     def discard(self, flag):
         """Remove flag bitmask if present.
 
diff --git a/tests/test_bitmask.py b/tests/test_bitmask.py
index 42539b7..b1ea889 100644
--- a/tests/test_bitmask.py
+++ b/tests/test_bitmask.py
@@ -11,21 +11,31 @@ class Desc(IntFlag):
     FUNKY = 1 << 2
     SONAR = 1 << 4
 
+class Colors(IntFlag):
+    TEAL = 1
+    PINK = 1 << 1
+    BLUE = 1 << 2
+
 def test_eq():
     """Test equality checks."""
+    # Equality
     assert Bitmask(Desc) == Bitmask(Desc)
     assert Bitmask(Desc, Desc.SMALL) == Bitmask(Desc, Desc.SMALL)
     assert Bitmask(Desc, Desc.SMALL, Desc.ROUND) == Bitmask(Desc, Desc.SMALL, Desc.ROUND)
     assert Bitmask(Desc, Desc.ROUND, Desc.SMALL) == Bitmask(Desc, Desc.SMALL, Desc.ROUND)
 
+    # Inequality
     assert Bitmask(Desc, Desc.SMALL) != Bitmask(Desc, Desc.SMALL, Desc.ROUND)
     assert Bitmask(Desc, Desc.SMALL) != Bitmask(Desc, Desc.ROUND)
     assert Bitmask(Desc, Desc.SMALL) != Bitmask(Desc)
     assert Bitmask(Desc, Desc.SMALL) != Desc.SMALL
     assert Bitmask(Desc, Desc.SMALL) != Desc.ROUND
     assert Bitmask(Desc) != Desc.ROUND
+
+    # Wrong types
     assert Bitmask(Desc) != "Hello World!"
     assert Bitmask(Desc) != 0
+    assert Bitmask(Desc) != Bitmask(Colors)
 
 def test_repr():
     """Ensure evaluating __repr__ creates an identical object."""
@@ -49,6 +59,8 @@ def test_add():
 
     with pytest.raises(TypeError, match="can only apply Desc to Bitmask"):
         mask.add(1)
+    with pytest.raises(TypeError, match="can only apply Bitmask or Desc to Bitmask"):
+        mask += 1
 
 def test_add_operator():
     """Test + operator."""