diff --git a/pkgs/applications/version-management/mercurial/default.nix b/pkgs/applications/version-management/mercurial/default.nix
index 8320491758ea..a85844fff216 100644
--- a/pkgs/applications/version-management/mercurial/default.nix
+++ b/pkgs/applications/version-management/mercurial/default.nix
@@ -78,7 +78,7 @@ let
       EOF
 
       # extended timeout necessary for tests to pass on the busy CI workers
-      export HGTESTFLAGS="--blacklist blacklists/nix --timeout 600"
+      export HGTESTFLAGS="--blacklist blacklists/nix --timeout 1800"
       make check
     '';