diff --git a/bindings/python/notmuch/database.py b/bindings/python/notmuch/database.py
index 9fb30e63..e18381ba 100644
--- a/bindings/python/notmuch/database.py
+++ b/bindings/python/notmuch/database.py
@@ -569,7 +569,7 @@ class Query(object):
         # create query, return None if too little mem available
         query_p = Query._create(db.db_p, _str(querystr))
         if query_p is None:
-            NotmuchError(STATUS.NULL_POINTER)
+            raise NotmuchError(STATUS.NULL_POINTER)
         self._query = query_p
 
     def set_sort(self, sort):
@@ -637,7 +637,7 @@ class Query(object):
         msgs_p = Query._search_messages(self._query)
 
         if msgs_p is None:
-            NotmuchError(STATUS.NULL_POINTER)
+            raise NotmuchError(STATUS.NULL_POINTER)
 
         return Messages(msgs_p, self)
 
diff --git a/bindings/python/notmuch/filename.py b/bindings/python/notmuch/filename.py
index 630886d7..a16e717e 100644
--- a/bindings/python/notmuch/filename.py
+++ b/bindings/python/notmuch/filename.py
@@ -68,7 +68,7 @@ class Filenames(object):
              once all derived objects are dead.
         """
         if files_p is None:
-            NotmuchError(STATUS.NULL_POINTER)
+            raise NotmuchError(STATUS.NULL_POINTER)
 
         self._files = files_p
         #save reference to parent object so we keep it alive
diff --git a/bindings/python/notmuch/message.py b/bindings/python/notmuch/message.py
index e5f60621..0c3365b5 100644
--- a/bindings/python/notmuch/message.py
+++ b/bindings/python/notmuch/message.py
@@ -115,7 +115,7 @@ class Messages(object):
                the Python object.(?)
         """
         if msgs_p is None:
-            NotmuchError(STATUS.NULL_POINTER)
+            raise NotmuchError(STATUS.NULL_POINTER)
 
         self._msgs = msgs_p
         #store parent, so we keep them alive as long as self  is alive
@@ -290,7 +290,7 @@ class Message(object):
               objects are dead.
         """
         if msg_p is None:
-            NotmuchError(STATUS.NULL_POINTER)
+            raise NotmuchError(STATUS.NULL_POINTER)
         self._msg = msg_p
         #keep reference to parent, so we keep it alive
         self._parent = parent
diff --git a/bindings/python/notmuch/tag.py b/bindings/python/notmuch/tag.py
index 0f25b0f7..50e3686b 100644
--- a/bindings/python/notmuch/tag.py
+++ b/bindings/python/notmuch/tag.py
@@ -70,7 +70,7 @@ class Tags(object):
                cache the tags in the Python object(?)
         """
         if tags_p is None:
-            NotmuchError(STATUS.NULL_POINTER)
+            raise NotmuchError(STATUS.NULL_POINTER)
 
         self._tags = tags_p
         #save reference to parent object so we keep it alive
diff --git a/bindings/python/notmuch/thread.py b/bindings/python/notmuch/thread.py
index 83b4202d..5e08eb31 100644
--- a/bindings/python/notmuch/thread.py
+++ b/bindings/python/notmuch/thread.py
@@ -95,7 +95,7 @@ class Threads(object):
                the Python object.(?)
         """
         if threads_p is None:
-            NotmuchError(STATUS.NULL_POINTER)
+            raise NotmuchError(STATUS.NULL_POINTER)
 
         self._threads = threads_p
         #store parent, so we keep them alive as long as self  is alive
@@ -206,7 +206,7 @@ class Thread(object):
               objects are dead.
         """
         if thread_p is None:
-            NotmuchError(STATUS.NULL_POINTER)
+            raise NotmuchError(STATUS.NULL_POINTER)
         self._thread = thread_p
         #keep reference to parent, so we keep it alive
         self._parent = parent
@@ -263,7 +263,7 @@ class Thread(object):
         msgs_p = Thread._get_toplevel_messages(self._thread)
 
         if msgs_p is None:
-            NotmuchError(STATUS.NULL_POINTER)
+            raise NotmuchError(STATUS.NULL_POINTER)
 
         return Messages(msgs_p, self)