diff --git a/mkosi.images/system/mkosi.repart/10-root.conf b/mkosi.images/system/mkosi.repart/10-root.conf
index 715b9254630..3c25dbfb14d 100644
--- a/mkosi.images/system/mkosi.repart/10-root.conf
+++ b/mkosi.images/system/mkosi.repart/10-root.conf
@@ -2,7 +2,7 @@
 
 [Partition]
 Type=root
-Format=ext4
+Format=btrfs
 CopyFiles=/
 SizeMinBytes=8G
 SizeMaxBytes=8G