diff --git a/docs/aunit.texi b/docs/aunit.texi
index d67c866..598e176 100644
--- a/docs/aunit.texi
+++ b/docs/aunit.texi
@@ -542,6 +542,8 @@ end Money_Suite;}
 
 Note that @code{New_Suite} and @code{Create} are fully compatible with
 limited run-times (in particular, those without dynamic allocation support).
+Note, however, that for non-native run-time libraries, you cannot extend
+@{Test_Fixture} with a controlled component.
 
 You can find a compilable example of
 @code{AUnit.Test_Caller} use in the AUnit installation