diff --git a/Doxyfile.in b/Doxyfile.in
index 5e33a777..3b491c31 100644
--- a/Doxyfile.in
+++ b/Doxyfile.in
@@ -842,7 +842,7 @@ INCLUDE_FILE_PATTERNS  =
 # or name=definition (no spaces). If the definition and the = are
 # omitted =1 is assumed.
 
-PREDEFINED             = VMIME_BUILDING_DOC VMIME_HAVE_SASL_SUPPORT VMIME_HAVE_TLS_SUPPORT VMIME_HAVE_MESSAGING_FEATURES VMIME_HAVE_MESSAGING_PROTO_POP3 VMIME_HAVE_MESSAGING_PROTO_SMTP VMIME_HAVE_MESSAGING_PROTO_IMAP VMIME_HAVE_MESSAGING_PROTO_MAILDIR VMIME_HAVE_MESSAGING_PROTO_SENDMAIL
+PREDEFINED             = VMIME_BUILDING_DOC VMIME_HAVE_SASL_SUPPORT VMIME_HAVE_TLS_SUPPORT VMIME_HAVE_FILESYSTEM_FEATURES VMIME_HAVE_MESSAGING_FEATURES VMIME_HAVE_MESSAGING_PROTO_POP3 VMIME_HAVE_MESSAGING_PROTO_SMTP VMIME_HAVE_MESSAGING_PROTO_IMAP VMIME_HAVE_MESSAGING_PROTO_MAILDIR VMIME_HAVE_MESSAGING_PROTO_SENDMAIL
 
 # 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.