diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,12 @@
+4.3.12
+
+* Fix space leak introduced in version 4.3.10
+    * This leak primarily affects the use of `forever`
+
+4.3.11
+
+* Fix documentation for `scanM`
+
 4.3.10
 
 * Relax `Monad` constraints to `Functor`
diff --git a/pipes.cabal b/pipes.cabal
--- a/pipes.cabal
+++ b/pipes.cabal
@@ -1,5 +1,5 @@
 Name: pipes
-Version: 4.3.11
+Version: 4.3.12
 Cabal-Version: >= 1.10
 Build-Type: Simple
 Tested-With: GHC == 7.10.3, GHC == 8.0.2, GHC == 8.2.2, GHC == 8.4.4, GHC == 8.6.5, GHC == 8.8.1
diff --git a/src/Pipes/Internal.hs b/src/Pipes/Internal.hs
--- a/src/Pipes/Internal.hs
+++ b/src/Pipes/Internal.hs
@@ -90,6 +90,12 @@
             Respond b  fb' -> Respond b  (\b' -> go (fb' b'))
             M          m   -> M (go <$> m)
             Pure    f      -> fmap f px
+    l *> r = go l where
+        go p = case p of
+            Request a' fa  -> Request a' (\a  -> go (fa  a ))
+            Respond b  fb' -> Respond b  (\b' -> go (fb' b'))
+            M          m   -> M (go <$> m)
+            Pure    _      -> r
 
 instance Functor m => Monad (Proxy a' a b' b m) where
     return = pure