diff --git a/src/Control/Monad/Base.hs b/src/Control/Monad/Base.hs
--- a/src/Control/Monad/Base.hs
+++ b/src/Control/Monad/Base.hs
@@ -5,14 +5,18 @@
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE UndecidableInstances #-}
 
+#if MIN_VERSION_base(4,4,0)
+{-# LANGUAGE Safe #-}
+#endif
+
 #if MIN_VERSION_transformers(0,4,0)
 -- Hide warnings for the deprecated ErrorT transformer:
 {-# OPTIONS_GHC -fno-warn-warnings-deprecations #-}
 #endif
 
-module Control.Monad.Base (
-    MonadBase(..),
-    liftBaseDefault
+module Control.Monad.Base
+  ( MonadBase(..)
+  , liftBaseDefault
   ) where
 
 import Data.Monoid
@@ -38,17 +42,17 @@
 
 #if !MIN_VERSION_base(4,4,0) && HS_TRANSFORMERS_BASE__ORPHANS
 import Control.Monad (ap)
-#endif
-
-#if MIN_VERSION_base(4,4,0) || HS_TRANSFORMERS_BASE__ORPHANS
 import qualified Control.Monad.ST.Lazy as L
 import qualified Control.Monad.ST.Strict as S
 #endif
 
-#if MIN_VERSION_base(4,3,0)
-import GHC.Conc.Sync (STM)
+#if MIN_VERSION_base(4,4,0)
+import qualified Control.Monad.ST.Lazy.Safe as L
+import qualified Control.Monad.ST.Safe as S
 #endif
 
+import Control.Monad.STM (STM)
+
 class (Applicative b, Applicative m, Monad b, Monad m)
       ⇒ MonadBase b m | m → b where
   -- | Lift a computation from the base monad
@@ -64,9 +68,7 @@
 BASE((→) r)
 BASE(Identity)
 
-#if MIN_VERSION_base(4,3,0)
 BASE(STM)
-#endif
 
 #if !MIN_VERSION_base(4,4,0) && HS_TRANSFORMERS_BASE__ORPHANS
 instance Applicative (L.ST s) where
@@ -76,9 +78,12 @@
 instance Applicative (S.ST s) where
   pure  = return
   (<*>) = ap
+
+BASE(L.ST s)
+BASE(S.ST s)
 #endif
 
-#if MIN_VERSION_base(4,4,0) || HS_TRANSFORMERS_BASE__ORPHANS
+#if MIN_VERSION_base(4,4,0)
 BASE(L.ST s)
 BASE(S.ST s)
 #endif
diff --git a/transformers-base.cabal b/transformers-base.cabal
--- a/transformers-base.cabal
+++ b/transformers-base.cabal
@@ -1,5 +1,5 @@
 Name: transformers-base
-Version: 0.4.2
+Version: 0.4.3
 Category: Control
 Stability: experimental
 Synopsis: Lift computations from the bottom of a transformer stack
@@ -34,8 +34,9 @@
 
 Library
   Build-Depends:
-    base          >= 3 && < 5,
-    transformers  >= 0.2
+    base         >= 3 && < 5,
+    stm          >= 2.3,
+    transformers >= 0.2
   Hs-Source-Dirs: src
   GHC-Options: -Wall
   if flag(OrphanInstances)