diff --git a/snaplet-recaptcha.cabal b/snaplet-recaptcha.cabal
index c91d09b..3454224 100644
--- a/snaplet-recaptcha.cabal
+++ b/snaplet-recaptcha.cabal
@@ -49,7 +49,7 @@ Library
   Hs-Source-Dirs:   src
   Exposed-Modules:  Snap.Snaplet.ReCaptcha
   Default-Language: Haskell2010
-  Build-Depends:    base
+  Build-Depends:    base >= 4 && < 5
                   , data-lens
                   , data-lens-template
                   , bytestring
@@ -65,7 +65,7 @@ Executable          recaptcha-test
   Hs-Source-Dirs:   src
   Other-Modules:    Snap.Snaplet.ReCaptcha
   Default-Language: Haskell2010
-  Build-Depends:    base
+  Build-Depends:    base >= 4 && < 5
                   , data-lens
                   , data-lens-template
                   , bytestring