diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,13 @@
 # Revision history for reflex
 
+## 0.6.4.1
+
+* Fix a bug in the Reflex Profiled transformer where
+  `Reflex.Class.mergeIncrementalG` and
+  `Reflex.Class.mergeIncrementalWithMoveG` implementations referenced
+  itself instead of the inner transformed timeline, causing an
+  infinite loop.
+
 ## 0.6.4
 
 * Support GHC 8.8
diff --git a/reflex.cabal b/reflex.cabal
--- a/reflex.cabal
+++ b/reflex.cabal
@@ -1,5 +1,5 @@
 Name: reflex
-Version: 0.6.4
+Version: 0.6.4.1
 Synopsis: Higher-order Functional Reactive Programming
 Description: Reflex is a high-performance, deterministic, higher-order Functional Reactive Programming system
 License: BSD3
diff --git a/src/Reflex/Profiled.hs b/src/Reflex/Profiled.hs
--- a/src/Reflex/Profiled.hs
+++ b/src/Reflex/Profiled.hs
@@ -147,8 +147,8 @@
   updated (Dynamic_Profiled d) = coerce $ profileEvent $ updated d
   unsafeBuildDynamic (ProfiledM a0) (Event_Profiled a') = coerce $ unsafeBuildDynamic a0 a'
   unsafeBuildIncremental (ProfiledM a0) (Event_Profiled a') = coerce $ unsafeBuildIncremental a0 a'
-  mergeIncrementalG nt = (Event_Profiled . coerce) #. mergeIncrementalG nt
-  mergeIncrementalWithMoveG nt = (Event_Profiled . coerce) #. mergeIncrementalWithMoveG nt
+  mergeIncrementalG nt res = Event_Profiled $ mergeIncrementalG (coerce nt) (coerce res)
+  mergeIncrementalWithMoveG nt res = Event_Profiled $ mergeIncrementalWithMoveG (coerce nt) (coerce res)
   currentIncremental (Incremental_Profiled i) = coerce $ currentIncremental i
   updatedIncremental (Incremental_Profiled i) = coerce $ profileEvent $ updatedIncremental i
   incrementalToDynamic (Incremental_Profiled i) = coerce $ incrementalToDynamic i
diff --git a/test/Reflex/Test/CrossImpl.hs b/test/Reflex/Test/CrossImpl.hs
--- a/test/Reflex/Test/CrossImpl.hs
+++ b/test/Reflex/Test/CrossImpl.hs
@@ -21,6 +21,7 @@
 import Reflex.Host.Class
 import qualified Reflex.Pure as P
 import qualified Reflex.Spider.Internal as S
+import qualified Reflex.Profiled as Prof
 
 import Control.Arrow (second, (&&&))
 import Control.Monad.Identity hiding (forM, forM_, mapM, mapM_, sequence, sequence_)
@@ -35,8 +36,6 @@
 import System.Exit
 import System.Mem
 
-import System.IO.Unsafe
-
 mapToPureBehavior :: Map Int a -> Behavior PureReflexDomain a
 mapToPureBehavior m = P.Behavior $ \t -> case Map.lookupLE t m of
   Nothing -> error $ "mapToPureBehavior: no value for time " <> show t
@@ -73,11 +72,14 @@
 instance (MapMSignals a a' t t', MapMSignals b b' t t') => MapMSignals (a, b) (a', b') t t' where
   mapMSignals fb fe (a, b) = liftM2 (,) (mapMSignals fb fe a) (mapMSignals fb fe b)
 
-testSpider :: (forall m t. TestCaseConstraint t m => (Behavior t a, Event t b) -> m (Behavior t c, Event t d)) -> (Map Int a, Map Int b) -> (Map Int c, Map Int d)
-testSpider builder (bMap, eMap) = unsafePerformIO $ S.runSpiderHost $ do
+testTimeline
+  :: (forall m t. TestCaseConstraint t m => (Behavior t a, Event t b) -> m (Behavior t c, Event t d))
+  -> (Map Int a, Map Int b)
+  -> (forall m t. (MonadReflexHost t m, MonadIO m, MonadRef m, Ref m ~ Ref IO, MonadSample t m) => m (Map Int c, Map Int d))
+testTimeline builder (bMap, eMap) = do
   (re, reTrigger) <- newEventWithTriggerRef
   (rb, rbTrigger) <- newEventWithTriggerRef
-  b <- runHostFrame $ hold (error "testSpider: No value for input behavior yet") rb
+  b <- runHostFrame $ hold (error "testTimeline: No value for input behavior yet") rb
   (b', e') <- runHostFrame $ builder (b, re)
   e'Handle <- subscribeEvent e' --TODO: This should be unnecessary
   let times = relevantTestingTimes (bMap, eMap)
@@ -102,9 +104,11 @@
 testAgreement builder inputs = do
   let identityResult = testPure builder inputs
   tracePerf "---------" $ return ()
-  let spiderResult = testSpider builder inputs
+  spiderResult <- S.runSpiderHost $ testTimeline builder inputs
   tracePerf "---------" $ return ()
-  let resultsAgree = identityResult == spiderResult
+  profiledResult <- S.runSpiderHost $ Prof.runProfiledM $ testTimeline builder inputs
+  tracePerf "---------" $ return ()
+  let resultsAgree = identityResult == spiderResult && identityResult == profiledResult
   if resultsAgree
     then do --putStrLn "Success:"
             --print identityResult
@@ -112,6 +116,7 @@
     else do putStrLn "Failure:"
             putStrLn $ "Pure result: " <> show identityResult
             putStrLn $ "Spider result:   " <> show spiderResult
+            putStrLn $ "Profiled result:   " <> show profiledResult
   return resultsAgree
 
 type TestCaseConstraint t m = (Reflex t, MonadSample t m, MonadHold t m, MonadFix m, MonadFix (PushM t))