diff --git a/nixbld-etc-nixos/configuration.nix b/nixbld-etc-nixos/configuration.nix
index a6b9a93a..c7a1c8f0 100644
--- a/nixbld-etc-nixos/configuration.nix
+++ b/nixbld-etc-nixos/configuration.nix
@@ -946,6 +946,12 @@ in
       hydraPath = oa.hydraPath + ":" + super.lib.makeBinPath [ super.jq ];
       doCheck = false;  # FIXME: ldap tests fail on hydra rebuild, seems unrelated to patches above.
     });
+    mattermost = super.mattermost.overrideAttrs(oa: {
+      postInstall = oa.postInstall +
+        ''
+        sed -i.bak "s/FREE EDITION//g" $out/client/*.js $out/client/*.js.map
+        '';
+    });
     matterbridge = super.matterbridge.overrideAttrs(oa: {
       patches = oa.patches or [] ++ [ ./matterbridge-disable-github.patch ];
     });