diff --git a/image-recipe/_archived/test-iso-qemu.sh b/image-recipe/_archived/test-iso-qemu.sh
index f44521e1..ec2d6f8a 100755
--- a/image-recipe/_archived/test-iso-qemu.sh
+++ b/image-recipe/_archived/test-iso-qemu.sh
@@ -8,10 +8,14 @@
 #   --bios       Force legacy BIOS mode (default: UEFI)
 #   --nographic  No GUI window, serial console only (great for logging)
 #
-# Serial log is always written to /tmp/archipelago-qemu-serial.log
+# Serial log and the 20G test disk are written under ${TMPDIR:-/tmp} — set
+# TMPDIR to a disk-backed directory if /tmp is space-constrained (both were
+# previously hardcoded to /tmp, which could ENOSPC a tmpfs-backed /tmp on a
+# 20G sparse qcow2 regardless of what the caller set TMPDIR to).
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
-SERIAL_LOG="/tmp/archipelago-qemu-serial.log"
+QEMU_TMPDIR="${TMPDIR:-/tmp}"
+SERIAL_LOG="$QEMU_TMPDIR/archipelago-qemu-serial.log"
 FORCE_BIOS=false
 NOGRAPHIC=false
 TIMEOUT=0
@@ -64,7 +68,7 @@ echo "  Serial: $SERIAL_LOG"
 echo ""
 
 # Create test disk if it doesn't exist
-DISK="/tmp/archipelago-test-disk.qcow2"
+DISK="$QEMU_TMPDIR/archipelago-test-disk.qcow2"
 if [ ! -f "$DISK" ]; then
     echo "Creating 20GB test disk..."
     qemu-img create -f qcow2 "$DISK" 20G