diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index d9605cc5..b036a9eb 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -568,7 +568,9 @@ Makefile:
   extensions:
   - .mak
   filenames:
+  - makefile
   - Makefile
+  - GNUmakefile
 
 Mako:
   extensions: