diff --git a/pkgs/applications/science/logic/prover9/default.nix b/pkgs/applications/science/logic/prover9/default.nix
index 677c11d3749e..aa01469bfbb8 100644
--- a/pkgs/applications/science/logic/prover9/default.nix
+++ b/pkgs/applications/science/logic/prover9/default.nix
@@ -33,7 +33,7 @@ stdenv.mkDerivation {
 
   meta = with lib; {
     homepage = "https://www.cs.unm.edu/~mccune/mace4/";
-    license = license.gpl;
+    license = licenses.gpl1;
     description = "Automated theorem prover for first-order and equational logic";
     longDescription = ''
       Prover9 is a resolution/paramodulation automated theorem prover