diff --git a/src/server/gf-server.cabal b/src/server/gf-server.cabal
index 357951488..2cee4566d 100644
--- a/src/server/gf-server.cabal
+++ b/src/server/gf-server.cabal
@@ -61,6 +61,7 @@ executable pgf-service
        -- Install it in Ubuntu with: apt-get install libghc-fastcgi-dev
 
   build-depends: base >=4.2 && <5,
+                 mtl,
                  old-time,
                  directory,
                  filepath,