diff --git a/mesonbuild/backend/backends.py b/mesonbuild/backend/backends.py
index a322d5f..12fbbe1 100644
--- a/mesonbuild/backend/backends.py
+++ b/mesonbuild/backend/backends.py
@@ -56,9 +56,10 @@ class TestProtocol(enum.Enum):
         raise MesonException('unknown test format {}'.format(string))
 
     def __str__(self) -> str:
-        if self is self.EXITCODE:
+        cls = type(self)
+        if self is cls.EXITCODE:
             return 'exitcode'
-        elif self is self.GTEST:
+        elif self is cls.GTEST:
             return 'gtest'
         return 'tap'