diff --git a/Gemfile b/Gemfile
index 93934d03e421f642bce5bc5e1264d3057f774915..d41d75b250a2380156fa695b69c9da6bcd41a351 100644
--- a/Gemfile
+++ b/Gemfile
@@ -15,7 +15,7 @@ gem 'default_value_for', '~> 3.0.0'
 gem 'mysql2', '~> 0.4.5', group: :mysql
 gem 'pg', '~> 0.18.2', group: :postgres
 
-gem 'rugged', '~> 0.25.1.1'
+gem 'rugged', '~> 0.26.0'
 gem 'grape-route-helpers', '~> 2.0.0'
 
 gem 'faraday', '~> 0.12'
diff --git a/Gemfile.lock b/Gemfile.lock
index 77e87e2885fa71164d2480a1409ab8503376d34e..2483b0bf35c51eb77366cb96ad83e75f0dadc19f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -751,7 +751,7 @@ GEM
     rubyzip (1.2.1)
     rufus-scheduler (3.4.0)
       et-orbi (~> 1.0)
-    rugged (0.25.1.1)
+    rugged (0.26.0)
     safe_yaml (1.0.4)
     sanitize (2.1.0)
       nokogiri (>= 1.4.4)
@@ -1084,7 +1084,7 @@ DEPENDENCIES
   ruby-prof (~> 0.16.2)
   ruby_parser (~> 3.8)
   rufus-scheduler (~> 3.4)
-  rugged (~> 0.25.1.1)
+  rugged (~> 0.26.0)
   sanitize (~> 2.0)
   sass-rails (~> 5.0.6)
   scss_lint (~> 0.54.0)
diff --git a/lib/gitlab/git/commit.rb b/lib/gitlab/git/commit.rb
index 4dcaff5e0a083d04f5fefd7bd14f33e8008d696d..ca7e3a7c4bee196f97e443d3426ded5396c87950 100644
--- a/lib/gitlab/git/commit.rb
+++ b/lib/gitlab/git/commit.rb
@@ -336,7 +336,7 @@ module Gitlab
         begin
           raw_commit.to_mbox(options)
         rescue Rugged::InvalidError => ex
-          if ex.message =~ /Commit \w+ is a merge commit/
+          if ex.message =~ /commit \w+ is a merge commit/i
             'Patch format is not currently supported for merge commits.'
           end
         end