diff --git a/code/week07/src/Week07/EvenOdd.hs b/code/week07/src/Week07/EvenOdd.hs
index d4fda92..c8ae175 100644
--- a/code/week07/src/Week07/EvenOdd.hs
+++ b/code/week07/src/Week07/EvenOdd.hs
@@ -101,17 +101,20 @@ mkGameValidator game bsZero' bsOne' dat red ctx =
             traceIfFalse "not signed by first player"    (txSignedBy info (gFirst game))                                    &&
             traceIfFalse "commit mismatch"               (checkNonce bs nonce c)                                            &&
             traceIfFalse "missed deadline"               (to (gRevealDeadline game) `contains` txInfoValidRange info)       &&
-            traceIfFalse "wrong stake"                   (lovelaces (txOutValue ownInput) == (2 * gStake game))
+            traceIfFalse "wrong stake"                   (lovelaces (txOutValue ownInput) == (2 * gStake game))             &&
+            traceIfFalse "NFT must go to first player"   nftToFirst
 
         (GameDatum _ Nothing, ClaimFirst) ->
             traceIfFalse "not signed by first player"    (txSignedBy info (gFirst game))                                    &&
             traceIfFalse "too early"                     (from (1 + gPlayDeadline game) `contains` txInfoValidRange info)   &&
-            traceIfFalse "first player's stake missing"  (lovelaces (txOutValue ownInput) == gStake game)
+            traceIfFalse "first player's stake missing"  (lovelaces (txOutValue ownInput) == gStake game)                   &&
+            traceIfFalse "NFT must go to first player"   nftToFirst
 
         (GameDatum _ (Just _), ClaimSecond) ->
             traceIfFalse "not signed by second player"   (txSignedBy info (gSecond game))                                   &&
-            traceIfFalse "to early"                      (from (1 + gRevealDeadline game) `contains` txInfoValidRange info) &&
-            traceIfFalse "wrong stake"                   (lovelaces (txOutValue ownInput) == (2 * gStake game))
+            traceIfFalse "too early"                     (from (1 + gRevealDeadline game) `contains` txInfoValidRange info) &&
+            traceIfFalse "wrong stake"                   (lovelaces (txOutValue ownInput) == (2 * gStake game))             &&
+            traceIfFalse "NFT must go to first player"   nftToFirst
 
         _                              -> False
   where
@@ -141,6 +144,9 @@ mkGameValidator game bsZero' bsOne' dat red ctx =
             Zero -> bsZero'
             One  -> bsOne'
 
+    nftToFirst :: Bool
+    nftToFirst = assetClassValueOf (valuePaidTo info $ gFirst game) (gToken game) == 1
+
 data Gaming
 instance Scripts.ScriptType Gaming where
     type instance DatumType Gaming = GameDatum
diff --git a/code/week07/src/Week07/StateMachine.hs b/code/week07/src/Week07/StateMachine.hs
index f878911..03154c5 100644
--- a/code/week07/src/Week07/StateMachine.hs
+++ b/code/week07/src/Week07/StateMachine.hs
@@ -199,7 +199,7 @@ firstGame fp = do
         v      = lovelaceValueOf (fpStake fp)
         c      = fpChoice fp
         bs     = sha2_256 $ fpNonce fp `concatenate` if c == Zero then bsZero else bsOne
-    void $ mapError @w @s @SMContractError (pack . show) $ runInitialise client (GameDatum bs Nothing) v
+    void $ mapError' $ runInitialise client (GameDatum bs Nothing) v
     logInfo @String $ "made first move: " ++ show (fpChoice fp)
 
     void $ awaitSlot $ 1 + fpPlayDeadline fp