diff --git a/pkgs/servers/mail/public-inbox/default.nix b/pkgs/servers/mail/public-inbox/default.nix
index 9918d075a733..05dc98b466d4 100644
--- a/pkgs/servers/mail/public-inbox/default.nix
+++ b/pkgs/servers/mail/public-inbox/default.nix
@@ -78,8 +78,7 @@ let
     "v2mirror"
   ];
 
-  testConditions = with lib;
-    concatMapStringsSep " " (n: "! -name ${escapeShellArg n}.t") skippedTests;
+  testConditions = lib.concatMapStringsSep " " (n: "! -name ${lib.escapeShellArg n}.t") skippedTests;
 
 in