diff --git a/docs/doxygen/Doxyfile.all b/docs/doxygen/Doxyfile.all
index 2d639b9aae..889e97f16f 100644
--- a/docs/doxygen/Doxyfile.all
+++ b/docs/doxygen/Doxyfile.all
@@ -21,6 +21,6 @@ GENERATE_RTF           = NO
 GENERATE_MAN           = NO
 GENERATE_PERLMOD       = NO
 GENERATE_AUTOGEN_DEF   = NO
-GENERATE_TAGFILE       = NO
+GENERATE_TAGFILE       =
 
 HHC_LOCATION           = ~/.wine/drive_c/Programmi/HTMLHelpWorkshop/hhc.exe
diff --git a/docs/doxygen/Doxyfile.chm b/docs/doxygen/Doxyfile.chm
index ebf136546f..588b65f28e 100644
--- a/docs/doxygen/Doxyfile.chm
+++ b/docs/doxygen/Doxyfile.chm
@@ -21,6 +21,6 @@ GENERATE_RTF           = NO
 GENERATE_MAN           = NO
 GENERATE_PERLMOD       = NO
 GENERATE_AUTOGEN_DEF   = NO
-GENERATE_TAGFILE       = NO
+GENERATE_TAGFILE       =
 
 HHC_LOCATION           = ~/.wine/drive_c/Programmi/HTMLHelpWorkshop/hhc.exe
diff --git a/docs/doxygen/Doxyfile.html b/docs/doxygen/Doxyfile.html
index 68b38e6907..21d08cda28 100644
--- a/docs/doxygen/Doxyfile.html
+++ b/docs/doxygen/Doxyfile.html
@@ -21,6 +21,6 @@ GENERATE_RTF           = NO
 GENERATE_MAN           = NO
 GENERATE_PERLMOD       = NO
 GENERATE_AUTOGEN_DEF   = NO
-GENERATE_TAGFILE       = NO
+GENERATE_TAGFILE       =
 
 HHC_LOCATION           =
diff --git a/docs/doxygen/Doxyfile.xml b/docs/doxygen/Doxyfile.xml
index 1f83485da0..19be391826 100644
--- a/docs/doxygen/Doxyfile.xml
+++ b/docs/doxygen/Doxyfile.xml
@@ -21,6 +21,6 @@ GENERATE_RTF           = NO
 GENERATE_MAN           = NO
 GENERATE_PERLMOD       = NO
 GENERATE_AUTOGEN_DEF   = NO
-GENERATE_TAGFILE       = NO
+GENERATE_TAGFILE       =
 
 HHC_LOCATION           =