diff --git a/bindings/python/notmuch/directory.py b/bindings/python/notmuch/directory.py
index 0c5e015e..284cbdce 100644
--- a/bindings/python/notmuch/directory.py
+++ b/bindings/python/notmuch/directory.py
@@ -177,7 +177,7 @@ class Directory(object):
 
     _destroy = nmlib.notmuch_directory_destroy
     _destroy.argtypes = [NotmuchDirectoryP]
-    _destroy.argtypes = None
+    _destroy.restype = None
 
     def __del__(self):
         """Close and free the Directory"""
diff --git a/bindings/python/notmuch/threads.py b/bindings/python/notmuch/threads.py
index 690206ef..225f5246 100644
--- a/bindings/python/notmuch/threads.py
+++ b/bindings/python/notmuch/threads.py
@@ -172,7 +172,7 @@ class Threads(Python3StringMixIn):
 
     _destroy = nmlib.notmuch_threads_destroy
     _destroy.argtypes = [NotmuchThreadsP]
-    _destroy.argtypes = None
+    _destroy.restype = None
 
     def __del__(self):
         """Close and free the notmuch Threads"""