diff --git a/src/RWS.hs b/src/RWS.hs
index f67b0a473..186976c5e 100644
--- a/src/RWS.hs
+++ b/src/RWS.hs
@@ -159,16 +159,15 @@ findNearestNeighbourTo canCompare kdTreeA kdTreeB term@(UnmappedTerm j _ b) = do
   (previous, unmappedA, unmappedB) <- get
   fromMaybe (insertion previous unmappedA unmappedB term) $ do
     -- Look up the nearest unmapped term in `unmappedA`.
-    foundA@(UnmappedTerm i _ a) <- nearestUnmapped canCompare (termsWithinMoveBoundsFrom previous unmappedA) kdTreeA term
+    foundA@(UnmappedTerm i _ a) <- nearestUnmapped canCompare (IntMap.filterWithKey (\ k (UnmappedTerm _ _ a) -> isInMoveBounds previous k && canCompareTerms canCompare a b) unmappedA) kdTreeA term
     -- Look up the nearest `foundA` in `unmappedB`
-    UnmappedTerm j' _ _ <- nearestUnmapped (flip canCompare) (termsWithinMoveBoundsFrom (pred j) unmappedB) kdTreeB foundA
+    UnmappedTerm j' _ _ <- nearestUnmapped (flip canCompare) (IntMap.filterWithKey (\ k (UnmappedTerm _ _ b) -> isInMoveBounds (pred j) k && canCompareTerms canCompare a b) unmappedB) kdTreeB foundA
     -- Return Nothing if their indices don't match
     guard (j == j')
     guard (canCompareTerms canCompare a b)
     pure $! do
       put (i, IntMap.delete i unmappedA, IntMap.delete j unmappedB)
       pure (These i j, These a b)
-    where termsWithinMoveBoundsFrom bound = IntMap.filterWithKey (\ k _ -> isInMoveBounds bound k)
 
 isInMoveBounds :: Int -> Int -> Bool
 isInMoveBounds previous i = previous < i && i < previous + defaultMoveBound