diff --git a/Data/Vector/Mutable/Dynamic.hs b/Data/Vector/Mutable/Dynamic.hs
--- a/Data/Vector/Mutable/Dynamic.hs
+++ b/Data/Vector/Mutable/Dynamic.hs
@@ -269,25 +269,29 @@
 -- | Read the back value and remove it from the vector. Throws an error if the vector is empty. 
 popBack :: PrimMonad m => MVector (PrimState m) a -> m a 
 popBack (MVector v) = do
-    MVectorData s v' <- readMutVar v
+    MVectorData s vec <- readMutVar v
     if (s <= 0) then
         error "Data.Vector.Mutable.Dynamic: popBack: empty vector"
     else do 
-        a <- MV.unsafeRead v' (s - 1)
-        when (s < quot (MV.length v') 2) $ do 
-            v'' <- MV.unsafeGrow v' (s - 1)
-            writeMutVar v (MVectorData (s - 1) v'')
+        a <- MV.unsafeRead vec (s - 1)
+        if (s < quot (MV.length vec) 2) then do
+            vec' <- MV.unsafeGrow vec (s - 1)
+            writeMutVar v (MVectorData (s - 1) vec')
+        else
+            writeMutVar v (MVectorData (s - 1) vec)
         return a 
 {-# INLINABLE popBack #-}
 
 -- | Read the back value and remove it from the vector, without checking.
 unsafePopBack :: PrimMonad m => MVector (PrimState m) a -> m a 
 unsafePopBack (MVector v) = do
-    MVectorData s v' <- readMutVar v
-    a <- MV.unsafeRead v' (s - 1)
-    when (s < quot (MV.length v') 2) $ do 
-        v'' <- MV.unsafeGrow v' (s - 1)
-        writeMutVar v (MVectorData (s - 1) v'')
+    MVectorData s vec <- readMutVar v
+    a <- MV.unsafeRead vec (s - 1)
+    if (s < quot (MV.length vec) 2) then do 
+        vec' <- MV.unsafeGrow vec (s - 1)
+        writeMutVar v (MVectorData (s - 1) vec')
+    else
+        writeMutVar v (MVectorData (s - 1) vec)        
     return a 
 {-# INLINABLE unsafePopBack #-}
 
diff --git a/dynamic-mvector.cabal b/dynamic-mvector.cabal
--- a/dynamic-mvector.cabal
+++ b/dynamic-mvector.cabal
@@ -1,6 +1,6 @@
 
 name:                dynamic-mvector
-version:             0.1.0.3
+version:             0.1.0.4
 synopsis:            A wrapper around MVector that enables pushing, popping and extending.     
 homepage:            https://github.com/AndrasKovacs/dynamic-mvector
 license:             BSD3
@@ -13,5 +13,5 @@
 
 library
   exposed-modules:     Data.Vector.Mutable.Dynamic
-  build-depends:       base >=4.7 && <4.9, primitive >=0.5 && <0.7, vector >=0.10 && <0.11
+  build-depends:       base >=4.7 && <4.9, primitive >=0.5 && <0.7, vector >=0.10
   default-language:    Haskell2010