diff --git a/Doc/lib/liburllib.tex b/Doc/lib/liburllib.tex
index a2ebc32..47348c1 100644
--- a/Doc/lib/liburllib.tex
+++ b/Doc/lib/liburllib.tex
@@ -29,6 +29,10 @@
 \method{read()}, \method{readline()}, \method{readlines()}, \method{fileno()},
 \method{close()}, \method{info()} and \method{geturl()}.  It also has
 proper support for the iterator protocol.
+One caveat: the \method{read()} method, if the size argument is
+omitted or negative, may not read until the end of the data stream;
+there is no good way to determine that the entire stream from a socket
+has been read in the general case.
 
 Except for the \method{info()} and \method{geturl()} methods,
 these methods have the same interface as for