diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # phash
 
+## 0.1.1.1
+
+  * Use mirror for convolutions
+  * Add `llvm` cabal flag
+
 ## 0.1.1.0
 
   * Add `with-phash` flag to enable `ForeignHash` module and benchmarks
diff --git a/perceptual-hash.cabal b/perceptual-hash.cabal
--- a/perceptual-hash.cabal
+++ b/perceptual-hash.cabal
@@ -1,6 +1,6 @@
 cabal-version: 2.0
 name: perceptual-hash
-version: 0.1.1.0
+version: 0.1.1.1
 license: BSD3
 license-file: LICENSE
 copyright: Copyright: (c) 2019 Vanessa McHale
@@ -22,6 +22,12 @@
     description:
         Use FFI bindings to pHash
 
+flag llvm
+    description:
+        Use LLVM backend to GHC rather than NCG
+    default: False
+    manual: True
+
 library
     exposed-modules:
         PerceptualHash
@@ -29,7 +35,7 @@
     other-modules:
         Median
     default-language: Haskell2010
-    other-extensions: FlexibleContexts
+    other-extensions: FlexibleContexts TypeFamilies
     ghc-options: -Wall -O2
     build-depends:
         base >=4.3 && <5,
@@ -39,7 +45,13 @@
         primitive -any,
         repa -any
 
+    if flag(llvm)
+        ghc-options: -fllvm
+
     if flag(with-phash)
+        pkgconfig-depends: pHash -any
+
+    if flag(with-phash)
         exposed-modules:
             ForeignHash
 
@@ -70,6 +82,9 @@
         par-traverse >=0.2.0.0,
         stm >=2.3
 
+    if flag(llvm)
+        ghc-options: -fllvm
+
     if impl(ghc >=8.0)
         ghc-options: -Wincomplete-uni-patterns -Wincomplete-record-updates
                      -Wredundant-constraints -Widentities
@@ -77,10 +92,28 @@
     if impl(ghc >=8.4)
         ghc-options: -Wmissing-export-lists
 
+test-suite perceptual-hash-test
+    type: exitcode-stdio-1.0
+    main-is: Spec.hs
+    hs-source-dirs: test
+    default-language: Haskell2010
+    ghc-options: -Wall -threaded -rtsopts -with-rtsopts=-N
+    build-depends:
+        base -any,
+        perceptual-hash -any,
+        hspec -any
+
+    if impl(ghc >=8.0)
+        ghc-options: -Wincomplete-uni-patterns -Wincomplete-record-updates
+                     -Wredundant-constraints -Widentities
+
+    if impl(ghc >=8.4)
+        ghc-options: -Wmissing-export-lists
+
 benchmark phash-bench
     type: exitcode-stdio-1.0
     main-is: Bench.hs
-    build-tools: cpphs -any
+    build-tool-depends: cpphs:cpphs -any
     hs-source-dirs: bench
     default-language: Haskell2010
     ghc-options: -threaded -rtsopts "-with-rtsopts=-N -qg" -Wall
@@ -91,8 +124,8 @@
         perceptual-hash -any,
         criterion -any
 
-    if flag(with-phash)
-        pkgconfig-depends: pHash -any
+    if flag(llvm)
+        ghc-options: -fllvm
 
     if flag(with-phash)
         cpp-options: -DFOREIGN_PHASH
diff --git a/src/PerceptualHash.hs b/src/PerceptualHash.hs
--- a/src/PerceptualHash.hs
+++ b/src/PerceptualHash.hs
@@ -10,11 +10,11 @@
 import           Data.Bits                (shiftL, (.|.))
 import qualified Data.Vector.Unboxed      as V
 import           Data.Word                (Word64)
-import           Graphics.Image           (Array, Bilinear (..), Border (Edge),
-                                           Image, Pixel (PixelX, PixelY),
-                                           RSU (..), X, Y, convolve, crop,
-                                           makeImage, readImageY, resize,
-                                           transpose, (|*|))
+import           Graphics.Image           (Array, Bilinear (..),
+                                           Border (Edge, Reflect), Image,
+                                           Pixel (PixelX, PixelY), RSU (..), X,
+                                           Y, convolve, crop, makeImage,
+                                           readImageY, resize, transpose, (|*|))
 import           Graphics.Image.Interface (Elevator, toVector)
 import           Median                   (median)
 
@@ -29,8 +29,8 @@
 
 {-# INLINE meanFilter #-}
 meanFilter :: (Fractional e, Array arr X e, Array arr cs e) => Image arr cs e -> Image arr cs e
-meanFilter = convolve Edge idMat
-{-# SCC meanFilter #-}
+meanFilter = convolve Reflect idMat
+-- {-# SCC meanFilter #-}
 
 {-# INLINE size32 #-}
 size32 :: Array arr cs e => Image arr cs e -> Image arr cs e
diff --git a/test/Spec.hs b/test/Spec.hs
new file mode 100644
--- /dev/null
+++ b/test/Spec.hs
@@ -0,0 +1,18 @@
+-- vim: syntax=hspec
+
+import           PerceptualHash (fileHash)
+import           Test.Hspec
+
+main :: IO ()
+main = hspec $
+    describe "fileHash" $ do
+
+        parallel $ it "should match when same" $ do
+            actual <- fileHash "demo-data/frog.jpeg"
+            expected <- fileHash "demo-data/frog.png"
+            actual `shouldBe` expected
+
+        parallel $ it "should not match when different" $ do
+            actual <- fileHash "demo-data/cat.png"
+            expected <- fileHash "demo-data/frog.png"
+            actual `shouldSatisfy` (/= expected)