diff --git a/CHANGES b/CHANGES
index 2e59a49..149f248 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,5 @@
+ - warn if trm() is called with undefined arguments
+
 0.49.6 2024-07-17 17:25:39 +0200 Tobias Oetiker <tobi@oetiker.ch>
 
  - fix some more memory loops
diff --git a/lib/CallBackery/Translate.pm b/lib/CallBackery/Translate.pm
index 3f84aa9..31b7913 100644
--- a/lib/CallBackery/Translate.pm
+++ b/lib/CallBackery/Translate.pm
@@ -130,8 +130,14 @@ use overload
     };
 
 sub trm ($str,@args) {
-    # make sure the arguments are stringified
-    return bless [$str,map { "$_" } @args];
+    # make sure the arguments are stringified, warn if undefined
+    return bless [$str,map {
+        if (not defined $_) {
+            my ($package, $filename, $line) = caller;
+            warn "Undefined argument for str='$str' from $package line $line";
+        }
+        "$_"
+    } @args];
 }
 
 =head2 $str->TO_JSON