diff --git a/Doc/lib/libfuncs.tex b/Doc/lib/libfuncs.tex
index 451c1a8..3104763 100644
--- a/Doc/lib/libfuncs.tex
+++ b/Doc/lib/libfuncs.tex
@@ -334,8 +334,9 @@
 
 \begin{funcdesc}{locals}{}
 Return a dictionary representing the current local symbol table.
-Inside a function, modifying this dictionary does not always have the
-desired effect.
+\strong{Warning:} the contents of this dictionary should not be
+modified; changes may not affect the values of local variables used by 
+the interpreter.
 \end{funcdesc}
 
 \begin{funcdesc}{long}{x}