diff --git a/Pyro5/serializers.py b/Pyro5/serializers.py
index 82100ac..dee7f27 100644
--- a/Pyro5/serializers.py
+++ b/Pyro5/serializers.py
@@ -422,7 +422,7 @@ def dumps(self, data):
         return msgpack.packb(data, use_bin_type=True, default=self.default)
 
     def loadsCall(self, data):
-        return msgpack.unpackb(self._convertToBytes(data), raw=False, object_hook=self.object_hook)
+        return msgpack.unpackb(self._convertToBytes(data), raw=False, object_hook=self.object_hook, ext_hook=self.ext_hook)
 
     def loads(self, data):
         return msgpack.unpackb(self._convertToBytes(data), raw=False, object_hook=self.object_hook, ext_hook=self.ext_hook)
diff --git a/tests/test_serialize.py b/tests/test_serialize.py
index 6ab92b0..92b46c0 100644
--- a/tests/test_serialize.py
+++ b/tests/test_serialize.py
@@ -111,6 +111,49 @@ class TestJsonSerializer(TestSerpentSerializer):
     class TestMsgpackSerializer(TestSerpentSerializer):
         serializer = Pyro5.serializers.serializers["msgpack"]
 
+    import msgpack
+
+    class Thing:
+        def __init__(self, value):
+            self.value = value
+
+    class CustomMsgpackSerializer(Pyro5.serializers.MsgpackSerializer):
+        CUSTOM_EXT_CODE = 0x40
+
+        def default(self, obj):
+            if isinstance(obj, Thing):
+                return msgpack.ExtType(self.CUSTOM_EXT_CODE, str(obj.value).encode("ascii"))
+            return super().default(obj)
+
+        def ext_hook(self, code, data):
+            if code == self.CUSTOM_EXT_CODE:
+                return Thing(int(data))
+            return super().ext_hook(code, data)
+
+    class TestMsgpackExtHookLoadsCall:
+        """Regression: MsgpackSerializer.loadsCall must honor ext_hook so
+        custom-ExtType-encoded call arguments round-trip when a subclass
+        overrides ext_hook for custom codes. Without the fix, loadsCall
+        returns raw msgpack.ExtType objects instead of decoded values."""
+
+        serializer = CustomMsgpackSerializer()
+
+        def testLoadsCallHonorsExtHook(self):
+            data = self.serializer.dumpsCall("obj-id", "method-name", (Thing(42),), {})
+            obj, method, vargs, kwargs = self.serializer.loadsCall(data)
+            assert obj == "obj-id"
+            assert method == "method-name"
+            assert isinstance(vargs[0], Thing)
+            assert vargs[0].value == 42
+            assert kwargs == {}
+
+        def testLoadsAlreadyHonorsExtHook(self):
+            """Sanity check on the sibling that always worked, so future
+            regressions on either method surface symmetrically."""
+            data = self.serializer.dumps(Thing(7))
+            back = self.serializer.loads(data)
+            assert isinstance(back, Thing)
+            assert back.value == 7
 
 class TestSerializer2_serpent:
     SERIALIZER = "serpent"