diff --git a/Dockerfile b/Dockerfile
index 5e911e3..7c85822 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -21,9 +21,9 @@ RUN echo 'debconf debconf/frontend select Noninteractive' | debconf-set-selectio
         echo "deb https://packages.sury.org/php/ $(lsb_release -sc) main" > /etc/apt/sources.list.d/php.list \
     ; fi \
     && apt-get update \
-    && apt-get install -y \
-        autoconf pkg-config \
-        php$PHP_VERSION-cli php-dev libevent-dev zlib1g-dev \
+    && apt-get install --no-install-recommends -y \
+        build-essential autoconf pkg-config patch \
+        php$PHP_VERSION-cli php$PHP_VERSION-dev libevent-dev zlib1g-dev \
     && if [ $ENABLE_IGBINARY -eq 1 ]; then apt-get install -y php-igbinary; fi \
     && if [ $ENABLE_MSGPACK -eq 1 ]; then apt-get install -y php-msgpack; fi \
     && apt-get clean
@@ -64,6 +64,7 @@ RUN rm -rf /build
 RUN if ldd `find /usr/lib/php/ -name memcached.so` | grep memcached; then exit 1; fi
 
 # check that the PHP extension can be loaded:
-RUN php -dextension=memcached.so -m | grep 'memcached' \
+RUN php -v \
+    && php -dextension=memcached.so -m | grep 'memcached' \
     && php -dextension=memcached.so -r 'new Memcached();' \
     && php -dextension=memcached.so -r 'if (!defined("Memcached::DYNAMIC_CLIENT_MODE")) exit(1);'
diff --git a/README.md b/README.md
index 61a95a1..7de8ef4 100644
--- a/README.md
+++ b/README.md
@@ -9,7 +9,7 @@
 ### Supported flavors
 
 - only Linux 64bit
-- PHP 7.1 through to PHP 7.4 - thanks to the sury.org PHP repository!
+- PHP 7.1 through to PHP 7.4 and also PHP 8 - thanks to the sury.org PHP repository!
 - with or without igbinary (`--build-arg ENABLE_IGBINARY=1`)
 - with or without msgpack (`--build-arg ENABLE_MSGPACK=1`)
 - with or without JSON (`--build-arg ENABLE_JSON=1`)
@@ -20,11 +20,11 @@
 1. Clone this repo
 2. `git submodule update --init`
 3. In the `aws-elasticache-cluster-client-*` repos, switch to the git branch that you want to build. Usually the default is fine.
-4. Build the library and the extension, either with or without support for igbinary serialization:
+4. Build the library and the extension, enable optional features using the `build-arg`s listed above:
     ```
     docker build --iidfile=/tmp/elasticache.docker \
         --build-arg PHP_VERSION=7.4 \
-        --build-arg ENABLE_IGBINARY=0 \
+        --build-arg ENABLE_JSON=1 \
         .
     ```
 5. Extract the freshly built PHP extension, optionally wrap into a tar file: