diff --git a/Containerfile b/Containerfile
index 976a03b66..d1f922739 100644
--- a/Containerfile
+++ b/Containerfile
@@ -36,7 +36,7 @@ RUN microdnf -y --setopt=install_weak_deps=0 --setopt=tsflags=nodocs install \
 
 WORKDIR /build
 COPY . .
-ENV PROTON_VERSION=main
+ENV PROTON_VERSION=0.40.0
 ENV PROTON_SOURCE_URL=${PROTON_SOURCE_URL:-https://github.com/apache/qpid-proton/archive/${PROTON_VERSION}.tar.gz}
 ENV LWS_VERSION=v4.3.3
 ENV LIBUNWIND_VERSION=v1.8.1