diff --git a/s3-bucket-list-qwarc b/s3-bucket-list-qwarc
index dcfae80..f7a57e2 100755
--- a/s3-bucket-list-qwarc
+++ b/s3-bucket-list-qwarc
@@ -232,10 +232,13 @@ printf '%s' "${code[@]#	}" >"${prefix}.py"  # That's a tab character after the h
 # Generate the markers file
 { if [[ -z "${noStartMarker}" ]]; then echo; fi; printf '%s\n' "$@"; if [[ -z "${noEndMarker}" ]]; then echo; fi; } >"${prefix}-markers"
 
+# Collect environment variables
+envvars=()
+envvars+=(S3BL_CMD="${cmd}")
+envvars+=(S3_FORMAT="${format}")
+envvars+=(S3_BUCKET_URL="${bucketUrl}")
+envvars+=(S3_MARKERS_FILENAME="${prefix}-markers")
+if [[ "${listUrls}" ]]; then envvars+=(S3_WITH_LIST_URLS="${listUrls}"); fi
+
 # Lift-off!
-S3BL_CMD="${cmd}" \
-  S3_FORMAT="${format}" \
-  S3_BUCKET_URL="${bucketUrl}" \
-  S3_MARKERS_FILENAME="${prefix}-markers" \
-  S3_WITH_LIST_URLS="${listUrls}" \
-  qwarc --concurrency "${concurrency}" --database "${prefix}.db" --log "${prefix}.log" --warc "${prefix}" "${prefix}.py"
+env "${envvars[@]}" qwarc --concurrency "${concurrency}" --database "${prefix}.db" --log "${prefix}.log" --warc "${prefix}" "${prefix}.py"