diff --git a/pkgs/development/libraries/mailcore2/default.nix b/pkgs/development/libraries/mailcore2/default.nix
index 4259e52510b..03a940801e9 100644
--- a/pkgs/development/libraries/mailcore2/default.nix
+++ b/pkgs/development/libraries/mailcore2/default.nix
@@ -21,6 +21,7 @@ stdenv.mkDerivation rec {
 
   postPatch = ''
     substituteInPlace CMakeLists.txt \
+       --replace " icule iculx" "" \
        --replace "tidy/tidy.h" "tidy.h" \
        --replace "/usr/include/tidy" "${libtidy}/include" \
        --replace "/usr/include/libxml2" "${libxml2.dev}/include/libxml2"