diff --git a/Containerfile b/Containerfile
index ecbc73e37..7c8c26f4a 100644
--- a/Containerfile
+++ b/Containerfile
@@ -55,7 +55,6 @@ LABEL maintainer="Mihai Criveti" \
       description="MCP Gateway: An enterprise-ready Model Context Protocol Gateway"
 
 ARG PYTHON_VERSION=3.12
-ARG TARGETPLATFORM
 ARG GRPC_PYTHON_BUILD_SYSTEM_OPENSSL='False'
 
 # Install Python and build dependencies
@@ -73,7 +72,7 @@ WORKDIR /app
 # s390x architecture does not support BoringSSL when building wheel grpcio.
 # Force Python whl to use OpenSSL.
 # ----------------------------------------------------------------------------
-RUN if [ "$TARGETPLATFORM" = "linux/s390x" ]; then \
+RUN if [ `uname -m` = "s390x" ]; then \
         echo "Building for s390x."; \
         echo "export GRPC_PYTHON_BUILD_SYSTEM_OPENSSL='True'" > /etc/profile.d/use-openssl.sh; \
     else \
diff --git a/Containerfile.lite b/Containerfile.lite
index 9e2e4d7aa..fd5ec6c3b 100644
--- a/Containerfile.lite
+++ b/Containerfile.lite
@@ -76,7 +76,6 @@ SHELL ["/bin/bash", "-euo", "pipefail", "-c"]
 
 ARG PYTHON_VERSION
 ARG ROOTFS_PATH
-ARG TARGETPLATFORM=linux/amd64
 ARG GRPC_PYTHON_BUILD_SYSTEM_OPENSSL='False'
 
 # ----------------------------------------------------------------------------
@@ -102,7 +101,7 @@ WORKDIR /app
 # s390x architecture does not support BoringSSL when building wheel grpcio.
 # Force Python whl to use OpenSSL.
 # ----------------------------------------------------------------------------
-RUN if [ "$TARGETPLATFORM" = "linux/s390x" ]; then \
+RUN if [ `uname -m` = "s390x" ]; then \
         echo "Building for s390x."; \
         echo "export GRPC_PYTHON_BUILD_SYSTEM_OPENSSL='True'" > /etc/profile.d/use-openssl.sh; \
     else \
diff --git a/Makefile b/Makefile
index 2fba48aeb..f6b279601 100644
--- a/Makefile
+++ b/Makefile
@@ -2098,7 +2098,7 @@ endif
 # =============================================================================
 
 # Auto-detect container runtime if not specified - DEFAULT TO DOCKER
-CONTAINER_RUNTIME = $(shell command -v docker >/dev/null 2>&1 && echo docker || echo podman)
+CONTAINER_RUNTIME ?= $(shell command -v docker >/dev/null 2>&1 && echo docker || echo podman)
 
 # Alternative: Always default to docker unless explicitly overridden
 # CONTAINER_RUNTIME ?= docker