diff --git a/docker/prepare.sh b/docker/prepare.sh
index 260faf3994b..a56d03f4077 100644
--- a/docker/prepare.sh
+++ b/docker/prepare.sh
@@ -9,9 +9,9 @@ echo "--- unpacking bases for snapcraft/$RISK ---"
 # and unpack them in the proper place.
 BASES="core core18 core20 core22"
 for base in $BASES; do
-    curl -L $(curl -H "X-Ubuntu-Series: 16" "https://api.snapcraft.io/api/v1/snaps/details/$base" | jq ".download_url" -r) --output $base.snap
-    mkdir -p /snap/$base
-    unsquashfs -d /snap/$base/current $base.snap
+    curl -L "$(curl -H "X-Ubuntu-Series: 16" "https://api.snapcraft.io/api/v1/snaps/details/$base" | jq ".download_url" -r)" --output "$base.snap"
+    mkdir -p "/snap/$base"
+    unsquashfs -d "/snap/$base/current" "$base.snap"
 done
 
 
@@ -19,6 +19,6 @@ echo "--- unpacking snapcraft/$RISK ---"
 
 # Grab the snapcraft snap from the $RISK channel and unpack it in the proper
 # place.
-curl -L $(curl -H 'X-Ubuntu-Series: 16' 'https://api.snapcraft.io/api/v1/snaps/details/snapcraft?channel='$RISK | jq '.download_url' -r) --output snapcraft.snap
+curl -L "$(curl -H "X-Ubuntu-Series: 16" "https://api.snapcraft.io/api/v1/snaps/details/snapcraft?channel=$RISK" | jq ".download_url" -r)" --output snapcraft.snap
 mkdir -p /snap/snapcraft
 unsquashfs -d /snap/snapcraft/current snapcraft.snap