diff --git a/lib/rouge/lexers/cobol.rb b/lib/rouge/lexers/cobol.rb
index 3bf59db2c6..cceb046ca4 100644
--- a/lib/rouge/lexers/cobol.rb
+++ b/lib/rouge/lexers/cobol.rb
@@ -7,7 +7,7 @@ class COBOL < RegexLexer
       title 'COBOL'
       desc 'COBOL (Common Business-Oriented Language) programming language'
       tag 'cobol'
-      filenames '*.cob', '*.cbl'
+      filenames '*.cob', '*.cbl', '*.cpy', '*.cpb'
       mimetypes 'text/x-cobol'
 
       identifier = /\p{Alpha}[\p{Alnum}-]*/
diff --git a/spec/lexers/cobol_spec.rb b/spec/lexers/cobol_spec.rb
index 17f15395cd..ce2fc5115f 100644
--- a/spec/lexers/cobol_spec.rb
+++ b/spec/lexers/cobol_spec.rb
@@ -70,6 +70,8 @@
     it 'guesses by filename' do
       assert_guess :filename => 'foo.cob'
       assert_guess :filename => 'foo.cbl'
+      assert_guess :filename => 'foo.cpy'
+      assert_guess :filename => 'foo.cpb'
     end
 
     it 'guesses by mimetype' do