diff --git a/pkgs/development/python-modules/affine-gaps/default.nix b/pkgs/development/python-modules/affine-gaps/default.nix
index 3529e64d56a2..1935c5d7f7fa 100644
--- a/pkgs/development/python-modules/affine-gaps/default.nix
+++ b/pkgs/development/python-modules/affine-gaps/default.nix
@@ -18,7 +18,7 @@ buildPythonPackage (finalAttrs: {
   src = fetchFromGitHub {
     owner = "gata-bio";
     repo = "affine-gaps";
-    tag = "v${version}";
+    tag = "v${finalAttrs.version}";
     hash = "sha256-Nbm79gKuCMqcCWQCjk8O2bbnzXBvby6FB/YhzqeDIJw=";
   };