diff --git a/pkgs/build-support/alternatives/blas/default.nix b/pkgs/build-support/alternatives/blas/default.nix
index cf880677fddc..2fab523f6a94 100644
--- a/pkgs/build-support/alternatives/blas/default.nix
+++ b/pkgs/build-support/alternatives/blas/default.nix
@@ -31,7 +31,6 @@ let
                        else stdenv.hostPlatform.extensions.sharedLibrary;
 
 
-  isILP64 = blasProvider.blas64 or false;
   blasImplementation = lib.getName blasProvider;
 
 in