diff --git a/ChangeLog b/ChangeLog
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,4 @@
+0.15 Fixes a Prelude.undefined error
 0.14 Fixes a space leak, fixes integration being factor 2 off
 0.13 Removed Show from integrate, added cstep
 0.12 Fixed BehaviorFix, added integration
diff --git a/Control/FRPNow/Core.hs b/Control/FRPNow/Core.hs
--- a/Control/FRPNow/Core.hs
+++ b/Control/FRPNow/Core.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE LambdaCase,RecursiveDo, FlexibleContexts, ExistentialQuantification, Rank2Types,GeneralizedNewtypeDeriving  #-}
+{-# LANGUAGE DeriveDataTypeable, LambdaCase,RecursiveDo, FlexibleContexts, ExistentialQuantification, Rank2Types,GeneralizedNewtypeDeriving  #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Control.FRPNow.Core
@@ -511,7 +511,7 @@
 makeLazy :: M (Event a) -> M (Event a)
 makeLazy m =  ReaderT $ \env ->
        do n <- curRound (clock env)   
-          r <- newIORef undefined
+          r <- newIORef (error "should not have read lazy yet")
           modifyIORef (laziesRef env) (Lazy m r :)
           return (readLazyState n r)
 
@@ -535,7 +535,12 @@
 -- When given a event carrying a now computation, execute that now computation as soon as the event occurs.
 -- If the event has already occured when 'planNow' is called, then the 'Now' computation will be executed immediatly.
 planNow :: Event (Now a) -> Now (Event a)
-planNow e = Now $ plan makeStrongRef (getNow  <$> e)
+planNow e = Now $ 
+  do e' <- runE e
+     case e' of
+      Occ x -> pure <$> getNow x
+      Never -> return Never
+      _     -> plan makeStrongRef (getNow  <$> e)
 
 plan :: (forall v. IORef v -> IO (Ref (IORef v))) -> Event (M a) -> M (Event a)
 plan makeRef e = 
@@ -565,7 +570,7 @@
         let env = Env pr lr c
         let it = runReaderT (iteration e) env
         e <- runReaderT m env
-        schedule (runReaderT (iterationMeat e) env)
+        runReaderT (iterationMeat e) env
         return ()
 
 iteration :: Event a -> M (Maybe a)
diff --git a/frpnow.cabal b/frpnow.cabal
--- a/frpnow.cabal
+++ b/frpnow.cabal
@@ -1,5 +1,5 @@
 Name:                frpnow
-Version:             0.14
+Version:             0.15
 Synopsis:	     Principled practical FRP
 Description:         FRP with first-class behaviors and interalized IO, without space leaks
 License:             BSD3