diff --git a/runtime/doc/testing.txt b/runtime/doc/testing.txt
index be2896e..18f6b19 100644
--- a/runtime/doc/testing.txt
+++ b/runtime/doc/testing.txt
@@ -446,7 +446,7 @@
 
 
 assert_report({msg})					*assert_report()*
-		Report a test failure directly, using {msg}.
+		Report a test failure directly, using String {msg}.
 		Always returns one.
 
 		Can also be used as a |method|: >