diff --git a/doc/userguide/rules/dnp3-keywords.rst b/doc/userguide/rules/dnp3-keywords.rst
index 8876330615..36f5afd699 100644
--- a/doc/userguide/rules/dnp3-keywords.rst
+++ b/doc/userguide/rules/dnp3-keywords.rst
@@ -146,4 +146,4 @@ Example
 
 ::
 
-  dnp3_data; content:|c3 06|;
+  dnp3_data; content:"|c3 06|";