diff --git a/src/Data/Abstract/Heap.hs b/src/Data/Abstract/Heap.hs
index e601f9c14..00f0114b3 100644
--- a/src/Data/Abstract/Heap.hs
+++ b/src/Data/Abstract/Heap.hs
@@ -41,4 +41,4 @@ heapRestrict (Heap m) roots = Heap (Monoidal.filterWithKey (\ address _ -> Addre
 
 
 instance (Show location, Show (cell value)) => Show (Heap location cell value) where
-  showsPrec d (Heap heap) = showsUnaryWith showsPrec "Heap" d (Monoidal.pairs heap)
+  showsPrec d = showsUnaryWith showsPrec "Heap" d . Monoidal.pairs . unHeap