diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,12 @@
 # Changelog for the [`clash-ghc`](http://hackage.haskell.org/package/clash-ghc) package
 
+## 0.5.10 *July 9th 2015*
+* New features:
+  * Use new VHDL backend which outputs VHDL-93 instead of VHDL-2002: generated VHDL is now accepted by a larger number of tools.
+  * Treat all so-called bottom values (`error "FOO"`, `let x = x in x`, etc.) occuring in installed libraries as `undefined`.
+    Before, there were (very) rare situations where we couldn't find the expressions belonging to a function and demanded a BlackBox, even though we knew the expression would be a bottom value.
+    Now, we stop demanding a BlackBox for such a function and simply treat it as `undefined`, thus allowing a greater range of circuit descriptions that we can compile.
+
 ## 0.5.9 *June 26th 2015*
 * New features:
   * Use new verilog backend which outputs Verilog-2001 instead of Verilog-2005: generated Verilog is now accepted by Altera/Quartus
diff --git a/clash-ghc.cabal b/clash-ghc.cabal
--- a/clash-ghc.cabal
+++ b/clash-ghc.cabal
@@ -1,5 +1,5 @@
 Name:                 clash-ghc
-Version:              0.5.9
+Version:              0.5.10
 Synopsis:             CAES Language for Synchronous Hardware
 Description:
   CλaSH (pronounced ‘clash’) is a functional hardware description language that
@@ -70,9 +70,9 @@
                       unbound-generics          >= 0.1,
                       unordered-containers      >= 0.2.1.0,
 
-                      clash-lib                 >= 0.5.8,
+                      clash-lib                 >= 0.5.9,
                       clash-systemverilog       >= 0.5.7,
-                      clash-vhdl                >= 0.5.7.1,
+                      clash-vhdl                >= 0.5.8,
                       clash-verilog             >= 0.5.7,
                       clash-prelude             >= 0.9,
                       ghc-typelits-natnormalise >= 0.3
diff --git a/src-ghc/CLaSH/GHC/LoadInterfaceFiles.hs b/src-ghc/CLaSH/GHC/LoadInterfaceFiles.hs
--- a/src-ghc/CLaSH/GHC/LoadInterfaceFiles.hs
+++ b/src-ghc/CLaSH/GHC/LoadInterfaceFiles.hs
@@ -16,6 +16,7 @@
 import qualified Class
 import qualified CoreFVs
 import qualified CoreSyn
+import qualified Demand
 import           DynFlags    (unsafeGlobalDynFlags)
 import qualified GHC
 import qualified Id
@@ -139,8 +140,9 @@
                          CoreSyn.CoreBndr                     -- unlocatable Var
 loadExprFromTyThing bndr tyThing = case tyThing of
   GHC.AnId _id | Var.isId _id ->
-    let unfolding  = IdInfo.unfoldingInfo $ Var.idInfo _id
-        inlineInfo = IdInfo.inlinePragInfo $ Var.idInfo _id
+    let _idInfo    = Var.idInfo _id
+        unfolding  = IdInfo.unfoldingInfo _idInfo
+        inlineInfo = IdInfo.inlinePragInfo _idInfo
     in case unfolding of
       (CoreSyn.CoreUnfolding {}) ->
         case (BasicTypes.inl_inline inlineInfo,BasicTypes.inl_act inlineInfo) of
@@ -152,5 +154,10 @@
         let dcApp  = MkCore.mkCoreConApps dc es
             dfExpr = MkCore.mkCoreLams dfbndrs dcApp
         in Left (bndr,dfExpr)
+      CoreSyn.NoUnfolding
+        | Demand.isBottomingSig $ IdInfo.strictnessInfo _idInfo
+        -> Left (bndr,CoreSyn.mkTyApps (CoreSyn.Var MkCore.uNDEFINED_ID)
+                                       [Var.varType _id]
+                )
       _ -> Right bndr
   _ -> Right bndr