diff --git a/lib/trivial.nix b/lib/trivial.nix
index b5c5d325eaad..334d1029a103 100644
--- a/lib/trivial.nix
+++ b/lib/trivial.nix
@@ -710,8 +710,8 @@ in {
           # `builtins.warn` requires a string message, so we enforce that in our implementation, so that callers aren't accidentally incompatible with newer Nix versions.
           assert isString msg;
           if mustAbort
-          then builtins.trace "warning: ${msg}" (abort "NIX_ABORT_ON_WARN=true; warnings are treated as unrecoverable errors.")
-          else builtins.trace "warning: ${msg}" v
+          then builtins.trace "evaluation warning: ${msg}" (abort "NIX_ABORT_ON_WARN=true; warnings are treated as unrecoverable errors.")
+          else builtins.trace "evaluation warning: ${msg}" v
     );
 
   /**