diff --git a/sdk/eventhub/azure-eventhub/stress/Dockerfile b/sdk/eventhub/azure-eventhub/stress/Dockerfile
index de521bb3bf45..033b01c3fa0c 100644
--- a/sdk/eventhub/azure-eventhub/stress/Dockerfile
+++ b/sdk/eventhub/azure-eventhub/stress/Dockerfile
@@ -1,6 +1,6 @@
 # internal users should provide MCR registry to build via 'docker build . --build-arg REGISTRY="mcr.microsoft.com/mirror/docker/library/"'
 # public OSS users should simply leave this argument blank or ignore its presence entirely
-ARG REGISTRY=""
+ARG REGISTRY="mcr.microsoft.com/mirror/docker/library/"
 FROM ${REGISTRY}python:3.8-slim-buster
 
 WORKDIR /app
diff --git a/sdk/servicebus/azure-servicebus/stress/Dockerfile b/sdk/servicebus/azure-servicebus/stress/Dockerfile
index f13d54baff04..61c94647f7ee 100644
--- a/sdk/servicebus/azure-servicebus/stress/Dockerfile
+++ b/sdk/servicebus/azure-servicebus/stress/Dockerfile
@@ -1,6 +1,6 @@
 # internal users should provide MCR registry to build via 'docker build . --build-arg REGISTRY="mcr.microsoft.com/mirror/docker/library/"'
 # public OSS users should simply leave this argument blank or ignore its presence entirely
-ARG REGISTRY=""
+ARG REGISTRY="mcr.microsoft.com/mirror/docker/library/"
 FROM ${REGISTRY}python:3.8-slim-buster
 
 WORKDIR /app