diff --git a/rc-service/rc-service-console/Dockerfile b/rc-service/rc-service-console/Dockerfile
index dd54597e..a568916d 100644
--- a/rc-service/rc-service-console/Dockerfile
+++ b/rc-service/rc-service-console/Dockerfile
@@ -14,7 +14,15 @@ RUN apt-get update \
 
 WORKDIR /application
 COPY console-start/target/rc-service-console-*.jar /tmp/service-jars/
-RUN cp "$(ls -t /tmp/service-jars/rc-service-console-*.jar | head -n 1)" /application/service.jar \
+RUN set -e; \
+    jars="$(find /tmp/service-jars -maxdepth 1 -type f -name 'rc-service-console-*.jar' | sort)"; \
+    count="$(printf '%s\n' "$jars" | grep -c . || true)"; \
+    if [ "$count" -ne 1 ]; then \
+      echo "Expected exactly one rc-service-console jar, found $count:"; \
+      ls -la /tmp/service-jars; \
+      exit 1; \
+    fi; \
+    cp "$jars" /application/service.jar \
     && rm -rf /tmp/service-jars
 
 CMD exec java -Djava.security.egd=file:/dev/./urandom \
diff --git a/rc-service/rc-service-external/Dockerfile b/rc-service/rc-service-external/Dockerfile
index 550475f4..30e813ca 100644
--- a/rc-service/rc-service-external/Dockerfile
+++ b/rc-service/rc-service-external/Dockerfile
@@ -14,7 +14,15 @@ RUN apt-get update \
 
 WORKDIR /application
 COPY external-start/target/rc-service-external-*.jar /tmp/service-jars/
-RUN cp "$(ls -t /tmp/service-jars/rc-service-external-*.jar | head -n 1)" /application/service.jar \
+RUN set -e; \
+    jars="$(find /tmp/service-jars -maxdepth 1 -type f -name 'rc-service-external-*.jar' | sort)"; \
+    count="$(printf '%s\n' "$jars" | grep -c . || true)"; \
+    if [ "$count" -ne 1 ]; then \
+      echo "Expected exactly one rc-service-external jar, found $count:"; \
+      ls -la /tmp/service-jars; \
+      exit 1; \
+    fi; \
+    cp "$jars" /application/service.jar \
     && rm -rf /tmp/service-jars
 
 CMD exec java -Djava.security.egd=file:/dev/./urandom \