diff --git a/pkgs/development/r-modules/default.nix b/pkgs/development/r-modules/default.nix
index 242629cc190e..46b5a8012dd0 100644
--- a/pkgs/development/r-modules/default.nix
+++ b/pkgs/development/r-modules/default.nix
@@ -646,14 +646,14 @@ let
       cargo
       rustc
     ];
-    hSDM = [ pkgs.gsl ];
+    hSDM = [ pkgs.gsl ]; # for gsl-config
     harbinger = [ pkgs.glibcLocales ];
     heck = with pkgs; [
       cargo
       rustc
     ];
     hellorust = [ pkgs.cargo ];
-    hgwrr = [ pkgs.gsl ];
+    hgwrr = [ pkgs.gsl ]; # for gsl-config
     highs = [
       pkgs.which
       pkgs.cmake