diff --git a/data/macros.rust b/data/macros.rust
index 0940d06..3a92818 100644
--- a/data/macros.rust
+++ b/data/macros.rust
@@ -14,6 +14,7 @@
 
 %__global_rustflags %{build_rustflags}
 
+# Currently unused, retained for backwards compatibility.
 %__global_rustflags_toml [%{lua:
     for arg in string.gmatch(rpm.expand("%{build_rustflags}"), "%S+") do
         print('"' .. arg .. '", ')