diff --git a/HushGP.cabal b/HushGP.cabal
index 98afee4..23be124 100644
--- a/HushGP.cabal
+++ b/HushGP.cabal
@@ -50,7 +50,7 @@ library
 
     -- Other library packages from which modules are imported.
     build-depends:
-        base, containers
+        base, containers, lens
 
     -- Directories containing source files.
     hs-source-dirs:   src