diff --git a/doc/doxygen/api.in b/doc/doxygen/api.in
index b3d72b20..cf6b9c4c 100644
--- a/doc/doxygen/api.in
+++ b/doc/doxygen/api.in
@@ -2138,7 +2138,7 @@ 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             = __attribute__(x)=
 
 # 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