diff --git a/Control/Event.hs b/Control/Event.hs
--- a/Control/Event.hs
+++ b/Control/Event.hs
@@ -181,7 +181,7 @@
     evts <- readTVar (esEvents sys)
     let newMap :: Map UTCTime EventSet
         prev :: Maybe EventSet
-        (prev,newMap) = updateLookupWithKey (\_ (cnt, old) -> Just (cnt,delete num old)) clk evts
+        (prev,newMap) = insertLookupWithKey (\_ _ (cnt, old) -> (cnt,delete num old)) clk undefined evts
         ret = case prev of
 		Nothing -> False -- error "Canceling an event that never existed."
 		Just (_,p)  -> case lookup clk newMap of
diff --git a/control-event.cabal b/control-event.cabal
--- a/control-event.cabal
+++ b/control-event.cabal
@@ -1,5 +1,5 @@
 name:                control-event
-version:             1.1.0.1
+version:             1.1.0.2
 synopsis:            Event scheduling system.
 description:         Allows scheduling and canceling of IO actions to be
                      executed at a specified future time.