diff --git a/README.md b/README.md
index f897746..27f6172 100644
--- a/README.md
+++ b/README.md
@@ -33,7 +33,7 @@ make
 
 You can add debug prints with
 ```bash
-make CFLAGS=DEBUG
+make CFLAGS=-DDEBUG
 ```
 
 ## How?