diff --git a/meta-arm-bsp/classes/image_types_disk_img.bbclass b/meta-arm-bsp/classes/image_types_disk_img.bbclass
index ea7ba86c..78cc0d85 100644
--- a/meta-arm-bsp/classes/image_types_disk_img.bbclass
+++ b/meta-arm-bsp/classes/image_types_disk_img.bbclass
@@ -51,7 +51,7 @@ disk_img_createpart() {
     local imagefile="$1"
     local start="$2"
     local size="$3"
-    local fstype="${4:-ext4}"
+    local fstype="${4:-}"
     local content="${5:-}"
     local formatargs=""