diff --git a/nixos/release.nix b/nixos/release.nix
index 8b4b27a1ef2e..8400a957ffb3 100644
--- a/nixos/release.nix
+++ b/nixos/release.nix
@@ -12,7 +12,7 @@ let
 
   version = fileContents ../.version;
   versionSuffix =
-    (if stableBranch then "." else "beta") + "${toString nixpkgs.revCount - 428633}.${nixpkgs.shortRev}";
+    (if stableBranch then "." else "beta") + "${toString (nixpkgs.revCount - 428633)}.${nixpkgs.shortRev}";
 
   # Run the tests for each platform.  You can run a test by doing
   # e.g. ‘nix-build release.nix -A tests.login.x86_64-linux’,