diff --git a/manual/cowboy.md b/manual/cowboy.md
index c2ef8597..0eab0f8e 100644
--- a/manual/cowboy.md
+++ b/manual/cowboy.md
@@ -76,7 +76,7 @@ Exports
 > Start listening for SPDY connections. Returns the pid for this
 > listener's supervisor.
 
-### stop_listener(Ref) -> ok
+### stop_listener(Ref) -> ok | {error, not_found}
 
 > Types:
 >  *  Ref = ranch:ref()
diff --git a/src/cowboy.erl b/src/cowboy.erl
index 610a33a1..3e838d19 100644
--- a/src/cowboy.erl
+++ b/src/cowboy.erl
@@ -67,7 +67,7 @@ start_spdy(Ref, NbAcceptors, TransOpts, ProtoOpts)
 		ranch_ssl, TransOpts2, cowboy_spdy, ProtoOpts).
 
 %% @doc Stop a listener.
--spec stop_listener(ranch:ref()) -> ok.
+-spec stop_listener(ranch:ref()) -> ok | {error, not_found}.
 stop_listener(Ref) ->
 	ranch:stop_listener(Ref).