diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 74ea5200699..769c94c44b8 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -1601,6 +1601,7 @@ in
 
   boringtun = callPackage ../tools/networking/boringtun { };
 
+  # Upstream recommends qt5.12 and it doesn't build with qt5.15
   boomerang = libsForQt512.callPackage ../development/tools/boomerang { };
 
   boost-build = callPackage ../development/tools/boost-build { };