diff --git a/polymer/eduke32/platform/wiibuild.bat b/polymer/eduke32/platform/wiibuild.bat
index a6d124e0b..e5267d3f4 100644
--- a/polymer/eduke32/platform/wiibuild.bat
+++ b/polymer/eduke32/platform/wiibuild.bat
@@ -40,8 +40,8 @@ xcopy /e /q /y /EXCLUDE:%wiidir%\xcopy_exclude.txt package\common apps\mapster32
 xcopy /e /q /y /EXCLUDE:%wiidir%\xcopy_exclude.txt package\sdk apps\mapster32\
 
 "ls.exe" -l -R apps
-7z.exe a -mx9 -t7z eduke32-wii-r%rev%-debug-elf.7z *.elf -xr!*.svn*
-7z.exe a -mx9 -t7z eduke32-wii-r%rev%.7z apps -xr!*.svn*
+7z.exe a -mx9 -ms=on -t7z eduke32-wii-r%rev%-debug-elf.7z *.elf -xr!*.svn*
+7z.exe a -mx9 -ms=on -t7z eduke32-wii-r%rev%.7z apps -xr!*.svn*
 
 :end
 
diff --git a/polymer/synthesis.sh b/polymer/synthesis.sh
index 0a80c62f2..58fc6c6a8 100755
--- a/polymer/synthesis.sh
+++ b/polymer/synthesis.sh
@@ -113,8 +113,8 @@ function package_game_lunatic ()
 
 function package_execute ()
 {
-    echo 7zr a -mx9 -t7z $output/$date-$head/${*}_$date-$head.7z *
-    7zr a -mx9 -t7z $output/$date-$head/${*}_$date-$head.7z *
+    echo 7zr a -mx9 -ms=on -t7z $output/$date-$head/${*}_$date-$head.7z *
+    7zr a -mx9 -ms=on -t7z $output/$date-$head/${*}_$date-$head.7z *
 
     cd $top/$source