diff --git a/README b/README
index 1ea397a..2e81ccc 100644
--- a/README
+++ b/README
@@ -948,6 +948,9 @@
 		bytes are output before the console is initialised, the
 		earlier bytes are discarded.
 
+		Note that when printing the buffer a copy is made on the
+		stack so CONFIG_PRE_CON_BUF_SZ must fit on the stack.
+
 		'Sane' compilers will generate smaller code if
 		CONFIG_PRE_CON_BUF_SZ is a power of 2