diff --git a/test/shell/lvextend-snapshot-dmeventd.sh b/test/shell/lvextend-snapshot-dmeventd.sh
index 01fc843ed..e7040d385 100644
--- a/test/shell/lvextend-snapshot-dmeventd.sh
+++ b/test/shell/lvextend-snapshot-dmeventd.sh
@@ -19,7 +19,7 @@ extend() {
 }
 
 write_() {
-	dd if=/dev/zero of="$DM_DEV_DIR/$vg/snap" bs=1k count=$2 seek=$1 oflag=direct
+	dd if=/dev/zero of="$DM_DEV_DIR/$vg/snap" bs=1k count=$2 seek=$1 conv=fdatasync
 }
 
 percent_() {