diff --git a/scripts/start_sandbox.sh b/scripts/start_sandbox.sh
index 9a79319b..236b1621 100755
--- a/scripts/start_sandbox.sh
+++ b/scripts/start_sandbox.sh
@@ -50,7 +50,7 @@ run_args+=(--name "$IMAGE-$INDEX" --hostname "$IMAGE-$INDEX")
 run_args+=(--env "SANDBOX=$IMAGE-$INDEX")
 
 # pass TERM and COLORTERM to container to maintain terminal colors
-run_args+=(--env "TERM=$TERM" --env "COLORTERM=$COLORTERM")
+run_args+=(--env "TERM=${TERM:-}" --env "COLORTERM=${COLORTERM:-}")
 
 # enable debugging via node --inspect-brk (and $DEBUG_PORT) if DEBUG is set
 node_args=()
@@ -62,4 +62,4 @@ node_args+=("$CLI_PATH" "$@")
 
 # run gemini-code in sandbox container
 # use empty --authfile to skip unnecessary auth refresh overhead
-$CMD run "${run_args[@]}" --init --authfile <(echo '{}') --workdir "$WORKDIR" "$IMAGE" node "${node_args[@]}"
\ No newline at end of file
+$CMD run "${run_args[@]}" --init --authfile <(echo '{}') --workdir "$WORKDIR" "$IMAGE" node "${node_args[@]}"