diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index 5e2d0495..c356efbf 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -174,6 +174,7 @@ Assembly:
   - nasm
   extensions:
   - .asm
+  - .a51
 
 Augeas:
   type: programming