diff --git a/signal-server-patches/apply-patches.sh b/signal-server-patches/apply-patches.sh
new file mode 100755
index 0000000..ab4e9e9
--- /dev/null
+++ b/signal-server-patches/apply-patches.sh
@@ -0,0 +1,6 @@
+#!/bin/bash
+set -euo pipefail
+for patch in /tmp/signal-server-patches/*.patch; do
+  echo "patch -p1 < \$patch"
+  patch -p1 < $patch
+done
diff --git a/signal-server.Dockerfile b/signal-server.Dockerfile
index 3325a8b..3c9bf5a 100644
--- a/signal-server.Dockerfile
+++ b/signal-server.Dockerfile
@@ -3,7 +3,7 @@ RUN apt-get update && apt-get install -y openjdk-8-jdk-headless maven git
 RUN git -C /usr/local/src clone https://github.com/signalapp/Signal-Server
 WORKDIR /usr/local/src/Signal-Server
 COPY signal-server-patches /tmp/signal-server-patches
-RUN bash -exc "for patch in /tmp/signal-server-patches/*.patch; do patch -p1 $patch; done"
+RUN /tmp/signal-server-patches/apply-patches.sh
 RUN mvn install -DskipTests
 RUN ls -lha target