diff --git a/Language/Nock5K/Spec.lhs b/Language/Nock5K/Spec.lhs
--- a/Language/Nock5K/Spec.lhs
+++ b/Language/Nock5K/Spec.lhs
@@ -131,7 +131,7 @@
 
   *[a 10 [b c] d]   *[a 8 c 7 [0 3] d]
 
-> tar (a :- Atom 10 :- (b :- c) :- d) =
+> tar (a :- Atom 10 :- (b :- c) :- d) = tar (a :- c) `seq`
 >   tar (a :- Atom 8 :- c :- Atom 7 :- (Atom 0 :- Atom 3) :- d)
 
   *[a 10 b c]       *[a c]
diff --git a/hsnock.cabal b/hsnock.cabal
--- a/hsnock.cabal
+++ b/hsnock.cabal
@@ -1,5 +1,5 @@
 name                 : hsnock
-version              : 0.1.4
+version              : 0.2.0
 category             : Language
 license              : PublicDomain
 synopsis             : Nock 5K interpreter.
@@ -34,8 +34,10 @@
   type               : exitcode-stdio-1.0
   main-is            : test.hs
   build-depends      : base >=4.5 && <5
+                     , HUnit >=1.2
+                     , QuickCheck >=2.6
                      , parsec >=3.1
                      , readline >=1.0
-                     , QuickCheck >=2.6
                      , test-framework >=0.8
+                     , test-framework-hunit >=0.3
                      , test-framework-quickcheck2 >=0.3
diff --git a/test.hs b/test.hs
--- a/test.hs
+++ b/test.hs
@@ -1,7 +1,10 @@
 import Control.Applicative
+import qualified Control.Exception as C
 import Language.Nock5K
 import Test.Framework
+import Test.Framework.Providers.HUnit
 import Test.Framework.Providers.QuickCheck2
+import Test.HUnit
 import Test.QuickCheck
 import Text.ParserCombinators.Parsec (parse)
 import Text.Printf
@@ -35,7 +38,17 @@
     ifs c = Atom a :- Atom 6 :- (Atom 1 :- c) :- (Atom 4 :- Atom 0 :- Atom 1) :- (Atom 1 :- b)
     a = abs a'
 
-tests = [ testProperty "parse.show" prop_parse_show
-        , testProperty "decrement"  prop_dec
-        , testProperty "6_is_if"    prop_6_is_if
+test_hint_crash =
+  C.catch (nock bad `seq` assertFailure "Hint not evaluated")
+          (\e -> do let se = show (e :: C.ErrorCall)
+                    if se == "/a"
+                      then return ()
+                      else assertFailure $ "Exception: " ++ se)
+ where
+  bad = Atom 42 :- Atom 10 :- (Atom 0 :- Atom 0 :- Atom 2) :- Atom 0 :- Atom 1
+
+tests = [ testProperty "parse.show"    prop_parse_show
+        , testProperty "decrement"     prop_dec
+        , testProperty "6_is_if"       prop_6_is_if
+        , testCase     "10_hint_crash" test_hint_crash
         ]