diff --git a/modules/disk.sh b/modules/disk.sh
index b06f72ee15..7abb638063 100644
--- a/modules/disk.sh
+++ b/modules/disk.sh
@@ -60,7 +60,7 @@ disk_get_part_nums() {
 #  $3 - size (in 512 blocks)
 #  $4 - path to output file
 disk_extract_part() {
-    run_and_log_cmd "dd if=$1 of=$4 skip=${2}b bs=1M count=${3}b status=none iflag=count_bytes,skip_bytes"
+    run_and_log_cmd "dd if=$1 of=$4 skip=${2}b bs=1M count=${3}b status=none conv=sparse iflag=count_bytes,skip_bytes"
 }
 
 # Convert MiB to number of 512 sectors
@@ -98,7 +98,7 @@ disk_align_sectors() {
 # $2 - destination file
 # $3 - offset in number of 512 sectors
 disk_write_at_offset() {
-    run_and_log_cmd "dd if=${1} of=${2} seek=${3} conv=notrunc status=none"
+    run_and_log_cmd "dd if=${1} of=${2} seek=${3} bs=512 conv=notrunc,sparse status=none"
 }
 
 # Create file system image from directory content