diff --git a/doc/Doxyfile.in b/doc/Doxyfile.in
index 39bc16929e..6d3b4c08b8 100644
--- a/doc/Doxyfile.in
+++ b/doc/Doxyfile.in
@@ -2004,7 +2004,7 @@ INCLUDE_FILE_PATTERNS  =
 # recursively expanded use the := operator instead of the = operator.
 # This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
 
-PREDEFINED             =
+PREDEFINED             = DOC
 
 # If the MACRO_EXPANSION and EXPAND_ONLY_PREDEF tags are set to YES then this
 # tag can be used to specify a list of macro names that should be expanded. The