diff --git a/mopidy/exceptions.py b/mopidy/exceptions.py
index b8d183fb..00c19e9e 100644
--- a/mopidy/exceptions.py
+++ b/mopidy/exceptions.py
@@ -22,3 +22,7 @@ class SettingsError(MopidyException):
 
 class OptionalDependencyError(MopidyException):
     pass
+
+
+class ExtensionError(MopidyException):
+    pass
diff --git a/tests/exceptions_test.py b/tests/exceptions_test.py
index 5148ebaf..2bc838d7 100644
--- a/tests/exceptions_test.py
+++ b/tests/exceptions_test.py
@@ -19,3 +19,7 @@ class ExceptionsTest(unittest.TestCase):
     def test_optional_dependency_error_is_a_mopidy_exception(self):
         self.assert_(issubclass(
             exceptions.OptionalDependencyError, exceptions.MopidyException))
+
+    def test_extension_error_is_a_mopidy_exception(self):
+        self.assert_(issubclass(
+            exceptions.ExtensionError, exceptions.MopidyException))