diff --git a/autorun/autorun0 b/autorun/autorun0
index 3c7dd2b..9a96abe 100755
--- a/autorun/autorun0
+++ b/autorun/autorun0
@@ -43,7 +43,10 @@ find_results_partition() {
 
 setup_results_dir() {
     local part
-    if part="$(find_results_partition)"; then
+    if [[ -n "${RESULTS_DIR:-}" ]]; then
+        # Explicitly configured via config/default.env.
+        :
+    elif part="$(find_results_partition)"; then
         RESULTS_DIR="${part}/results"
         # Remount rw if we landed on a read-only mount
         mount -o remount,rw "$part" 2> /dev/null || true
@@ -51,7 +54,11 @@ setup_results_dir() {
         log "WARN: no writable FAT32 partition found; results will live in tmpfs (/run/results) and will NOT survive reboot"
         RESULTS_DIR=/run/results
     fi
-    mkdir -p "$RESULTS_DIR"
+    if ! mkdir -p "$RESULTS_DIR" 2> /dev/null; then
+        log "WARN: could not create RESULTS_DIR=$RESULTS_DIR; falling back to /run/results"
+        RESULTS_DIR=/run/results
+        mkdir -p "$RESULTS_DIR"
+    fi
     export RESULTS_DIR
 }
 
diff --git a/autorun/lib.sh b/autorun/lib.sh
index dd2f589..2b44571 100644
--- a/autorun/lib.sh
+++ b/autorun/lib.sh
@@ -1,12 +1,23 @@
 # Shared helpers for autorun test scripts.
 # Sourced by autorun0 and by each autorun/tests/*.sh.
 
-# Default config — overridden by /run/sysrescue-config/default.env if present
-# (build-rescue-usb.sh writes config/default.env to that location on the FAT32
-# partition).
+# Load the baked-in tunables. build-rescue-usb.sh writes config/default.env
+# onto the FAT32 partition, which SystemRescue mounts under
+# /run/sysrescue-config. Anything set there overrides the defaults below.
+for _cfg in /run/sysrescue-config/default.env /default.env; do
+    if [[ -r "$_cfg" ]]; then
+        # shellcheck disable=SC1090
+        source "$_cfg"
+        break
+    fi
+done
+unset _cfg
+
 : "${STRESS_DURATION_SEC:=7200}"
 : "${MEMTESTER_PCT:=95}"
-: "${RESULTS_DIR:=/run/results}"
+# Empty => autorun0 writes results to the writable FAT32 partition when one is
+# found (survives reboot); set an absolute path to override.
+: "${RESULTS_DIR:=}"
 
 section() {
     printf '\n=== %s ===\n' "$1"
diff --git a/config/default.env b/config/default.env
index b9bb437..5c46f43 100644
--- a/config/default.env
+++ b/config/default.env
@@ -9,5 +9,6 @@ STRESS_DURATION_SEC=7200
 # Percent of MemAvailable to test with memtester (default: 95)
 MEMTESTER_PCT=95
 
-# Where on the FAT32 partition to drop results files
-RESULTS_DIR=/run/results
+# Where to write results files. Leave unset to write to the writable FAT32
+# partition (so results survive reboot); set an absolute path to override.
+# RESULTS_DIR=/mnt/results