diff --git a/HISTORY b/HISTORY
index f68dd810..32edcc8b 100644
--- a/HISTORY
+++ b/HISTORY
@@ -9566,3 +9566,5 @@ Video Disk Recorder Revision History
 2021-01-02: Version 2.4.7
 
 - Fixed strreplace() to handle NULL strings (reported by Jürgen Schneider).
+- Somewhere down the road the 'x' bit of Doxyfile.filter got lost, so the
+  Makefile now makes sure it is set before calling doxygen.
diff --git a/Makefile b/Makefile
index 25d4a9ca..69a2892a 100644
--- a/Makefile
+++ b/Makefile
@@ -4,7 +4,7 @@
 # See the main source file 'vdr.c' for copyright information and
 # how to reach the author.
 #
-# $Id: Makefile 4.10 2020/06/27 09:13:04 kls Exp $
+# $Id: Makefile 4.10.1.1 2021/01/02 15:11:20 kls Exp $
 
 .DELETE_ON_ERROR:
 
@@ -342,6 +342,7 @@ install-pc: vdr.pc
 srcdoc:
 	@cat $(DOXYFILE) > $(DOXYFILE).tmp
 	@echo PROJECT_NUMBER = $(VDRVERSION) >> $(DOXYFILE).tmp
+	@chmod +x $(DOXYFILE).filter
 	$(DOXYGEN) $(DOXYFILE).tmp
 	@rm $(DOXYFILE).tmp