diff --git a/tests/pkg_fatfs/create_fat_image_file.sh b/tests/pkg_fatfs/create_fat_image_file.sh
index 057bdd29a0..db8a58c036 100755
--- a/tests/pkg_fatfs/create_fat_image_file.sh
+++ b/tests/pkg_fatfs/create_fat_image_file.sh
@@ -6,7 +6,7 @@
 # General Public License v2.1. See the file LICENSE in the top level
 # directory for more details.
 #
-dd if=/dev/zero of=riot_fatfs_disk.img bs=1M count=$1
+dd if=/dev/zero of=riot_fatfs_disk.img bs=1M count="$1"
 mkfs.fat riot_fatfs_disk.img
 sudo mkdir -p /media/riot_fatfs_disk
 sudo mount -o loop,umask=000 riot_fatfs_disk.img /media/riot_fatfs_disk
diff --git a/tests/pkg_fatfs_vfs/create_fat_image_file.sh b/tests/pkg_fatfs_vfs/create_fat_image_file.sh
index fa72597b7b..796b8bb373 100755
--- a/tests/pkg_fatfs_vfs/create_fat_image_file.sh
+++ b/tests/pkg_fatfs_vfs/create_fat_image_file.sh
@@ -6,7 +6,7 @@
 # General Public License v2.1. See the file LICENSE in the top level
 # directory for more details.
 #
-dd if=/dev/zero of=riot_fatfs_disk.img bs=1M count=$1
+dd if=/dev/zero of=riot_fatfs_disk.img bs=1M count="$1"
 mkfs.fat riot_fatfs_disk.img
 sudo mkdir -p /media/riot_fatfs_disk
 sudo mount -o loop,umask=000 riot_fatfs_disk.img /media/riot_fatfs_disk