diff --git a/devlib/utils/asyn.py b/devlib/utils/asyn.py
index 1bbf8bc..dd6d42d 100644
--- a/devlib/utils/asyn.py
+++ b/devlib/utils/asyn.py
@@ -217,6 +217,12 @@ class _AsyncPolymorphicFunction:
             blocking=self.blocking.__get__(*args, **kwargs),
         )
 
+    # Ensure inspect.iscoroutinefunction() does not detect us as being async,
+    # since __call__ is not.
+    @property
+    def __code__(self):
+        return self.__call__.__code__
+
     def __call__(self, *args, **kwargs):
         return self.blocking(*args, **kwargs)