diff --git a/src/Data/Graph/DGraph.hs b/src/Data/Graph/DGraph.hs
index b737d19..b3934e5 100644
--- a/src/Data/Graph/DGraph.hs
+++ b/src/Data/Graph/DGraph.hs
@@ -136,10 +136,8 @@ instance Graph DGraph where
         | otherwise = graph
             where v1Links' = HM.delete v2 $ getLinks v1 g
 
-
-    removeVertex v g@(DGraph s _) = DGraph s
-        $ (\(DGraph _ g') -> HM.delete v g')
-        $ foldl' (flip removeArc) g $ incidentArcs g v
+    removeVertex v g = DGraph s $ HM.delete v g'
+        where (DGraph s g') = foldl' (flip removeArc) g $ incidentArcs g v
 
     isSimple g = foldl' go True $ vertices g
         where go bool v = bool && not (HM.member v $ getLinks v $ unDGraph g)
diff --git a/src/Data/Graph/UGraph.hs b/src/Data/Graph/UGraph.hs
index a891470..12e24e7 100644
--- a/src/Data/Graph/UGraph.hs
+++ b/src/Data/Graph/UGraph.hs
@@ -116,9 +116,8 @@ instance Graph UGraph where
             v2Links = HM.delete v1 $ getLinks v2 g
             update = HM.adjust . const
 
-    removeVertex v g@(UGraph s _) = UGraph s
-        $ (\(UGraph _ g') -> HM.delete v g')
-        $ foldl' (flip removeEdge) g $ incidentEdges g v
+    removeVertex v g = UGraph s $ HM.delete v g'
+        where (UGraph s g') = foldl' (flip removeEdge) g $ incidentEdges g v
 
     isSimple g = foldl' go True $ vertices g
         where go bool v = bool && not (HM.member v $ getLinks v $ unUGraph g)
diff --git a/test/Data/Graph/DGraphSpec.hs b/test/Data/Graph/DGraphSpec.hs
index ddd191f..857d9bf 100644
--- a/test/Data/Graph/DGraphSpec.hs
+++ b/test/Data/Graph/DGraphSpec.hs
@@ -78,3 +78,6 @@ spec = do
             edgeTriples g2 `shouldBe` [(1, 2, 'a'), (2, 1, 'b')]
             length (arcs g2) `shouldBe` 2
 
+        it "Decrements its size when vertices incident to an arc are removed" $ property $
+            \g v -> (g `containsVertex` v) && (vertexDegree g v > 0) && (size g > 0)
+                ==> let g1 = removeVertex v (g :: DGraph Int ()) in size g1 == length (arcs g1)
diff --git a/test/Data/Graph/UGraphSpec.hs b/test/Data/Graph/UGraphSpec.hs
index 64f527e..107ca72 100644
--- a/test/Data/Graph/UGraphSpec.hs
+++ b/test/Data/Graph/UGraphSpec.hs
@@ -85,3 +85,7 @@ spec = do
             let g = insertEdge (Edge 3 4 'b') $ insertEdge (Edge 1 2 'a') empty :: UGraph Int Char
             edgeTriples g `shouldBe` [(1, 2, 'a'), (3, 4, 'b')]
             length (edges g) `shouldBe` 2
+
+        it "Decrements its size when vertices incident to an edge are removed" $ property $
+            \g v -> (g `containsVertex` v) && (vertexDegree g v > 0) && (size g > 0)
+                ==> let g1 = removeVertex v (g :: UGraph Int ()) in size g1 == length (edges g1)