diff --git a/Doxyfile b/Doxyfile
--- a/Doxyfile
+++ b/Doxyfile
@@ -202,7 +202,7 @@ SKIP_FUNCTION_MACROS   = YES
 # Configuration::additions related to external references
 #---------------------------------------------------------------------------
 TAGFILES               =
-GENERATE_TAGFILE       = openttd.tag
+GENERATE_TAGFILE       = objs/openttd.tag
 ALLEXTERNALS           = NO
 EXTERNAL_GROUPS        = YES
 PERL_PATH              = /usr/bin/perl