diff --git a/clang/docs/CommandGuide/diagtool.rst b/clang/docs/CommandGuide/diagtool.rst
index 59417f71f69d..656ce10b2331 100644
--- a/clang/docs/CommandGuide/diagtool.rst
+++ b/clang/docs/CommandGuide/diagtool.rst
@@ -9,7 +9,7 @@ SYNOPSIS
 DESCRIPTION
 -----------
 
-:program:`diagtool` is a combination of four tool for dealing with diagnostics in :program:`clang`.
+:program:`diagtool` is a combination of four tools for dealing with diagnostics in :program:`clang`.
 
 SUBCOMMANDS
 -----------