diff --git a/llvm-tf.cabal b/llvm-tf.cabal
--- a/llvm-tf.cabal
+++ b/llvm-tf.cabal
@@ -1,5 +1,5 @@
 Name:          llvm-tf
-Version:       3.1
+Version:       3.1.0.1
 License:       BSD3
 License-File:  LICENSE
 Synopsis:      Bindings to the LLVM compiler toolkit using type families.
@@ -39,7 +39,7 @@
   Location: http://code.haskell.org/~thielema/llvm-tf/
 
 Source-Repository this
-  Tag:      3.1
+  Tag:      3.1.0.1
   Type:     darcs
   Location: http://code.haskell.org/~thielema/llvm-tf/
 
diff --git a/src/LLVM/Core/CodeGenMonad.hs b/src/LLVM/Core/CodeGenMonad.hs
--- a/src/LLVM/Core/CodeGenMonad.hs
+++ b/src/LLVM/Core/CodeGenMonad.hs
@@ -9,15 +9,17 @@
     CodeGenFunction, runCodeGenFunction, liftCodeGenModule, genFSym, getFunction, getBuilder, getFunctionModule, getExterns, putExterns,
     ) where
 
-import LLVM.Core.Util (Module, Builder, Function)
+import LLVM.Core.Util (Module, Builder, Function, getValueNameU, withModule, )
 
 import qualified LLVM.FFI.Core as FFI
 import qualified LLVM.FFI.ExecutionEngine as EE
 
-import Foreign.Ptr (FunPtr, Ptr, )
+import Foreign.C.String (withCString, )
+import Foreign.Ptr (FunPtr, Ptr, nullPtr, )
 
 import Control.Monad.Trans.State (StateT, runStateT, evalStateT, get, gets, put, modify, )
 import Control.Monad.IO.Class (MonadIO, liftIO, )
+import Control.Monad (when, )
 import Control.Applicative (Applicative, )
 import Data.Monoid (Monoid, mempty, mappend, (<>), )
 
@@ -95,17 +97,41 @@
 
 addGlobalMapping ::
     Value -> Ptr a -> CodeGenModule ()
-addGlobalMapping value func = CGM $ modify $ \cgm ->
-    cgm { cgm_global_mappings =
-             cgm_global_mappings cgm <>
-             GlobalMappings (\ee -> EE.addGlobalMapping ee value func) }
+addGlobalMapping value func =
+    CGM $ addMappingToState $
+        GlobalMappings (\ee -> EE.addGlobalMapping ee value func)
 
 addFunctionMapping ::
     Function -> FunPtr f -> CodeGenModule ()
-addFunctionMapping value func = CGM $ modify $ \cgm ->
-    cgm { cgm_global_mappings =
-             cgm_global_mappings cgm <>
-             GlobalMappings (\ee -> EE.addFunctionMapping ee value func) }
+addFunctionMapping value func = CGM $ do
+    {-
+    We need to fetch the name from the value
+    since it might have been disambiguized after adding.
+    -}
+    name <- liftIO $ getValueNameU value
+    modul <- gets cgm_module
+    addMappingToState $
+        GlobalMappings $ \ee -> do
+            {-
+            Between adding and application
+            the program may have been restructured by optimization passes.
+            I have not seen that the optimizer alters a Function Value pointer,
+            but the optimizer can remove an unused function.
+            That would render the original value invalid.
+            -}
+            currentValue <-
+                liftIO $
+                    withCString name $ \cname ->
+                    withModule modul $ \cmodule ->
+                        FFI.getNamedFunction cmodule cname
+            -- the optimizer could have removed the function
+            when (currentValue/=nullPtr) $
+                EE.addFunctionMapping ee currentValue func
+
+addMappingToState :: GlobalMappings -> StateT CGMState IO ()
+addMappingToState gm =
+    modify $ \cgm ->
+        cgm { cgm_global_mappings = cgm_global_mappings cgm <> gm }
 
 newtype GlobalMappings =
     GlobalMappings (EE.ExecutionEngineRef -> IO ())