diff --git a/readme.md b/readme.md
index 4d441bf..b9afeca 100644
--- a/readme.md
+++ b/readme.md
@@ -174,7 +174,7 @@ For the complete actual CSS see
 
 Strikethrough sequences form with the following BNF:
 
-```bnf
+```abnf
 gfmAttentionSequence ::= 1*"~"
 ```