diff --git a/runtime/doc/usr_31.txt b/runtime/doc/usr_31.txt
index ff3dfbc..22ba60f 100644
--- a/runtime/doc/usr_31.txt
+++ b/runtime/doc/usr_31.txt
@@ -245,7 +245,7 @@
 
 	:set lines=55
 
-You don't want to do this in a terminal, since it's size is fixed (except for
+You don't want to do this in a terminal, since its size is fixed (except for
 an xterm that supports resizing).
    The gvimrc file is searched for in the same locations as the vimrc file.
 Normally its name is "~/.gvimrc" for Unix and "$VIM/_gvimrc" for MS-Windows.