diff --git a/Dockerfile b/Dockerfile
index 1488954..426139c 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -17,10 +17,28 @@ RUN apt-get update && \
 # Give IBC more time to detect the login/config dialog on the current headless
 # GCE target. The upstream 60s default has been too short during keepalive
 # recovery and caused intermittent exit code 1112 before the Gateway became
-# API-ready.
-RUN sed -i 's/^LoginDialogDisplayTimeout=60$/LoginDialogDisplayTimeout=180/' \
-    /home/ibgateway/ibc/config.ini \
-    /home/ibgateway/ibc/config.ini.tmpl
+# API-ready. Fail the image build if the setting is not actually applied.
+RUN python3 - <<'PY'
+from pathlib import Path
+import re
+
+paths = [
+    Path("/home/ibgateway/ibc/config.ini"),
+    Path("/home/ibgateway/ibc/config.ini.tmpl"),
+]
+for path in paths:
+    text = path.read_text(encoding="utf-8")
+    updated = re.sub(
+        r"(?m)^LoginDialogDisplayTimeout\s*=.*$",
+        "LoginDialogDisplayTimeout=180",
+        text,
+    )
+    if updated == text and "LoginDialogDisplayTimeout=180" not in text:
+        updated = f"{text.rstrip()}\nLoginDialogDisplayTimeout=180\n"
+    path.write_text(updated, encoding="utf-8")
+    if "LoginDialogDisplayTimeout=180" not in updated:
+        raise SystemExit(f"failed to set LoginDialogDisplayTimeout in {path}")
+PY
 
 COPY --chown=1000:1000 ./container_overrides/run.sh /home/ibgateway/scripts/run.sh
 RUN chmod a+x /home/ibgateway/scripts/run.sh
diff --git a/container_overrides/run.sh b/container_overrides/run.sh
index 536afa4..0fad2c2 100644
--- a/container_overrides/run.sh
+++ b/container_overrides/run.sh
@@ -63,6 +63,7 @@ start_vnc() {
 }
 
 start_IBC() {
+	configure_ibc_login_dialog_timeout
 	echo ".> Starting IBC in ${TRADING_MODE} mode, with params:"
 	echo ".>		Version: ${TWS_MAJOR_VRSN}"
 	echo ".>		program: ${IBC_COMMAND:-gateway}"
@@ -82,6 +83,27 @@ start_IBC() {
 	echo "$_p" >"/tmp/pid_${TRADING_MODE}"
 }
 
+configure_ibc_login_dialog_timeout() {
+	local timeout="${IBC_LOGIN_DIALOG_DISPLAY_TIMEOUT:-180}"
+	local files=(
+		"${IBC_INI:-/home/ibgateway/ibc/config.ini}"
+		"/home/ibgateway/ibc/config.ini"
+		"/home/ibgateway/ibc/config.ini.tmpl"
+	)
+	local file
+
+	for file in "${files[@]}"; do
+		if [ ! -f "$file" ]; then
+			continue
+		fi
+		if grep -Eq '^LoginDialogDisplayTimeout\s*=' "$file"; then
+			sed -i -E "s/^LoginDialogDisplayTimeout\s*=.*/LoginDialogDisplayTimeout=${timeout}/" "$file"
+		else
+			printf '\nLoginDialogDisplayTimeout=%s\n' "$timeout" >>"$file"
+		fi
+	done
+}
+
 start_process() {
 	set_ports
 	apply_settings
diff --git a/tests/test_docker_compose_ports.sh b/tests/test_docker_compose_ports.sh
index 44d7b2e..9e6ce1f 100644
--- a/tests/test_docker_compose_ports.sh
+++ b/tests/test_docker_compose_ports.sh
@@ -8,7 +8,8 @@ run_override="$repo_dir/container_overrides/run.sh"
 
 grep -Fq 'pip3 install pyotp ib_insync --break-system-packages' "$dockerfile"
 grep -Fq 'FROM gnzsnz/ib-gateway:10.37.1q' "$dockerfile"
-grep -Fq "LoginDialogDisplayTimeout=60$/LoginDialogDisplayTimeout=180" "$dockerfile"
+grep -Fq 'LoginDialogDisplayTimeout=180' "$dockerfile"
+grep -Fq 'failed to set LoginDialogDisplayTimeout' "$dockerfile"
 grep -Fq '/home/ibgateway/ibc/config.ini.tmpl' "$dockerfile"
 grep -Fq 'COPY --chown=1000:1000 ./container_overrides/run.sh /home/ibgateway/scripts/run.sh' "$dockerfile"
 grep -Fq 'chmod a+x /home/ibgateway/scripts/run.sh' "$dockerfile"
@@ -17,6 +18,9 @@ grep -Fq 'libglib2.0-0' "$dockerfile"
 grep -Fq 'libxtst6' "$dockerfile"
 grep -Fq 'Xvfb "$DISPLAY" -ac -screen 0 "${IB_XVFB_SCREEN:-1024x768x24}" &' "$run_override"
 grep -Fq -- '-ncache_cr -noxdamage' "$run_override"
+grep -Fq 'configure_ibc_login_dialog_timeout' "$run_override"
+grep -Fq 'IBC_LOGIN_DIALOG_DISPLAY_TIMEOUT:-180' "$run_override"
+grep -Fq 'LoginDialogDisplayTimeout=${timeout}' "$run_override"
 
 grep -Fq '      - "4001:4003"' "$compose_file"
 grep -Fq '      - "4002:4004"' "$compose_file"