diff --git a/runtime/doc/vimdiff.1 b/runtime/doc/vimdiff.1
index e487284..079aeed 100644
--- a/runtime/doc/vimdiff.1
+++ b/runtime/doc/vimdiff.1
@@ -32,8 +32,8 @@
 changes in a fold.  'foldcolumn' is set to two to make it easy to spot the
 folds and open or close them.
 .SH OPTIONS
-Vertical splits are used to align the lines, as if the "-O" argument was used.
-To use horizontal splits intead, use the "-o" argument.
+Vertical splits are used to align the lines, as if the "\-O" argument was used.
+To use horizontal splits intead, use the "\-o" argument.
 .PP
 For all other arguments see vim(1).
 .SH SEE ALSO