diff --git a/doc/CODING-GUIDELINES b/doc/CODING-GUIDELINES
index 80ab207675..c4cb675e74 100644
--- a/doc/CODING-GUIDELINES
+++ b/doc/CODING-GUIDELINES
@@ -41,6 +41,8 @@ can list them in the "svn diff" command:
 * General rules
 ---------------
 
+- Indent code using tabs, not spaces.
+
 - All code, filenames, function names and comments must be in ENGLISH.
 
 - Don't annotate your changes with comments like "/* JMG 4/20/04 */";