diff --git a/lib/pronto/formatter/github_formatter.rb b/lib/pronto/formatter/github_formatter.rb
index e0de75d4..9c0092e2 100644
--- a/lib/pronto/formatter/github_formatter.rb
+++ b/lib/pronto/formatter/github_formatter.rb
@@ -2,6 +2,8 @@ module Pronto
   module Formatter
     class GithubFormatter
       def format(messages, repo)
+        messages = messages.uniq { |message| [message.msg, message.line.new_lineno] }
+
         commit_messages = messages.map do |message|
           sha = message.commit_sha
           body = message.msg
diff --git a/lib/pronto/formatter/github_pull_request_formatter.rb b/lib/pronto/formatter/github_pull_request_formatter.rb
index a07f0fdb..db9223c3 100644
--- a/lib/pronto/formatter/github_pull_request_formatter.rb
+++ b/lib/pronto/formatter/github_pull_request_formatter.rb
@@ -2,6 +2,8 @@ module Pronto
   module Formatter
     class GithubPullRequestFormatter
       def format(messages, repo)
+        messages = messages.uniq { |message| [message.msg, message.line.new_lineno] }
+
         commit_messages = messages.map do |message|
           body = message.msg
           path = message.path
diff --git a/spec/pronto/formatter/github_formattter_spec.rb b/spec/pronto/formatter/github_formattter_spec.rb
index b6515541..e6132372 100644
--- a/spec/pronto/formatter/github_formattter_spec.rb
+++ b/spec/pronto/formatter/github_formattter_spec.rb
@@ -13,6 +13,33 @@ module Formatter
         let(:line) { double(new_lineno: 1, commit_sha: '123', position: nil) }
         before { line.stub(:commit_line).and_return(line) }
 
+        specify do
+          Octokit::Client.any_instance
+                         .should_receive(:commit_comments)
+                         .once
+                         .and_return([])
+
+          Octokit::Client.any_instance
+                         .should_receive(:create_commit_comment)
+                         .once
+
+          subject
+        end
+      end
+
+      describe '#format without duplicates' do
+        subject { github_formatter.format(messages, repository) }
+        let(:messages) { [message1, message2] }
+        let(:repository) { Git::Repository.new('.') }
+        let(:message1) { Message.new('path/to1', line1, :warning, 'crucial') }
+        let(:message2) { Message.new('path/to2', line2, :warning, 'crucial') }
+        let(:line1) { double(new_lineno: 1, commit_sha: '123', position: nil) }
+        let(:line2) { double(new_lineno: 2, commit_sha: '123', position: nil) }
+        before do
+          line1.stub(:commit_line).and_return(line1)
+          line2.stub(:commit_line).and_return(line2)
+        end
+
         specify do
           Octokit::Client.any_instance
                          .should_receive(:commit_comments)