diff --git a/src/couch_replicator/src/couch_replicator_auth.erl b/src/couch_replicator/src/couch_replicator_auth.erl
index 1c9a4972320..60273fc32fb 100644
--- a/src/couch_replicator/src/couch_replicator_auth.erl
+++ b/src/couch_replicator/src/couch_replicator_auth.erl
@@ -33,7 +33,8 @@
 
 % Behavior API
 
--callback initialize(#httpdb{}) -> {ok, #httpdb{}, term()} | ignore.
+-callback initialize(#httpdb{}) ->
+    {ok, #httpdb{}, term()} | {error, term()} | ignore.
 
 -callback update_headers(term(), headers()) -> {headers(), term()}.
 
diff --git a/src/couch_replicator/src/couch_replicator_auth_session.erl b/src/couch_replicator/src/couch_replicator_auth_session.erl
index 3fff295725a..fedc4c66871 100644
--- a/src/couch_replicator/src/couch_replicator_auth_session.erl
+++ b/src/couch_replicator/src/couch_replicator_auth_session.erl
@@ -100,7 +100,8 @@
 
 % Behavior API callbacks
 
--spec initialize(#httpdb{}) -> {ok, #httpdb{}, term()} | ignore.
+-spec initialize(#httpdb{}) ->
+    {ok, #httpdb{}, term()} | {error, term()} | ignore.
 initialize(#httpdb{} = HttpDb) ->
     case init_state(HttpDb) of
         {ok, HttpDb1, State} ->