diff --git a/NEWS.md b/NEWS.md
index 8d01eefc16..0cec76cece 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -130,7 +130,7 @@ The following bundled gems are updated.
 * rexml 3.3.9
 * rss 0.3.1
 * net-ftp 0.3.8
-* net-imap 0.5.0
+* net-imap 0.5.1
 * net-smtp 0.5.0
 * rbs 3.6.1
 * typeprof 0.21.11
diff --git a/gems/bundled_gems b/gems/bundled_gems
index c53618dc5d..5e5f89fa8d 100644
--- a/gems/bundled_gems
+++ b/gems/bundled_gems
@@ -13,7 +13,7 @@ test-unit           3.6.2   https://github.com/test-unit/test-unit
 rexml               3.3.9   https://github.com/ruby/rexml
 rss                 0.3.1   https://github.com/ruby/rss
 net-ftp             0.3.8   https://github.com/ruby/net-ftp
-net-imap            0.5.0   https://github.com/ruby/net-imap
+net-imap            0.5.1   https://github.com/ruby/net-imap
 net-pop             0.1.2   https://github.com/ruby/net-pop
 net-smtp            0.5.0   https://github.com/ruby/net-smtp
 matrix              0.4.2   https://github.com/ruby/matrix