diff --git a/Dockerfile b/Dockerfile
index 06b3689..757d1d3 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -9,6 +9,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     tzdata \
     xvfb \
     x11vnc \
+    x11-utils \
     novnc \
     websockify \
     fluxbox \
diff --git a/docker/entrypoint.sh b/docker/entrypoint.sh
index f16a020..bac874c 100755
--- a/docker/entrypoint.sh
+++ b/docker/entrypoint.sh
@@ -29,10 +29,16 @@ echo "[entrypoint] starting Xvfb on ${DISPLAY} (${GEOMETRY})"
 Xvfb "${DISPLAY}" -screen 0 "${GEOMETRY}" -ac +extension RANDR &
 XVFB_PID=$!
 
-# Give Xvfb a moment to come up.
-for _ in 1 2 3 4 5 6 7 8 9 10; do
-  if xdpyinfo -display "${DISPLAY}" >/dev/null 2>&1; then break; fi
+# Give Xvfb a moment to come up. Requires x11-utils (xdpyinfo).
+for i in $(seq 1 50); do
+  if xdpyinfo -display "${DISPLAY}" >/dev/null 2>&1; then
+    echo "[entrypoint] Xvfb is ready after ${i} checks"
+    break
+  fi
   sleep 0.2
+  if [ "${i}" = "50" ]; then
+    echo "[entrypoint] WARNING: Xvfb did not respond after 10s" >&2
+  fi
 done
 
 # Minimal window manager so dialogs and tabs aren't stuck behind the root window.