diff --git a/knowledge base/duperemove.md b/knowledge base/duperemove.md
index c6f396b..0aad9bd 100644
--- a/knowledge base/duperemove.md	
+++ b/knowledge base/duperemove.md	
@@ -12,7 +12,7 @@ When given the `-d` option, `duperemove` also submits duplicated extents for ded
 
 ## TL;DR
 
-```shell
+```sh
 # Recursively search for duplicated extents in a directory.
 duperemove -hr path/to/directory