diff --git a/Dockerfile b/Dockerfile
index 77461ba..898c61f 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -9,5 +9,6 @@ FROM azul/zulu-openjdk-alpine:25
 COPY --from=build /build/target/btcprice-standalone.jar /btcprice/btcprice-standalone.jar
 
 EXPOSE 4040
+ENV PORT=4040
 
 CMD ["java", "-jar", "/btcprice/btcprice-standalone.jar"]