diff --git a/core/federated/RTI/rti.Dockerfile b/core/federated/RTI/rti.Dockerfile
index 0103abde8..bbe4f9d97 100644
--- a/core/federated/RTI/rti.Dockerfile
+++ b/core/federated/RTI/rti.Dockerfile
@@ -1,5 +1,5 @@
 ARG BASEIMAGE=alpine:latest 
-FROM ${BASEIMAGE} as builder
+FROM ${BASEIMAGE} AS builder
 COPY . /lingua-franca
 WORKDIR /lingua-franca/core/federated/RTI
 RUN set -ex && apk add --no-cache gcc musl-dev cmake make && \
@@ -12,7 +12,7 @@ RUN set -ex && apk add --no-cache gcc musl-dev cmake make && \
 WORKDIR /lingua-franca
 
 # application stage
-FROM ${BASEIMAGE} as app
+FROM ${BASEIMAGE} AS app
 LABEL maintainer="lf-lang"
 LABEL source="https://github.com/lf-lang/reactor-c/tree/main/core/federated/RTI"
 COPY --from=builder /usr/local/bin/RTI /usr/local/bin/RTI