diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 544f6d3..32f1efb 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php: ["7.0","7.1","7.2","7.3"]
+        php: ["7.0","7.1","7.2","7.3","7.4"]
     steps:
     - uses: actions/checkout@v1
     - name: enable experimental features
diff --git a/Dockerfile b/Dockerfile
index 522cd76..182fd55 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,5 +1,5 @@
   
-ARG PHP=7.1
+ARG PHP=7.4
 FROM php:$PHP-apache
 #libs: libjudy-dev need this for memprof
 ARG libs="libfreetype6 libjpeg62-turbo liblz4-tool libjudy-dev"
@@ -11,7 +11,8 @@ ARG RUNTIME_PACKAGE_DEPS="$libs $tools msmtp bc locales"
 
 ARG BUILD_PACKAGE_DEPS="libcurl4-openssl-dev libjpeg-dev libpng-dev libxml2-dev libzip-dev"
 
-ARG PHP_EXT_DEPS="curl json xml mbstring zip bcmath soap pdo_mysql gd mysqli"
+
+ARG PHP_EXT_DEPS="curl json xml zip bcmath soap pdo_mysql gd mysqli"
 ARG PECL_DEPS="memprof xdebug"
 ARG PHP_MEMORY_LIMIT="-1"
 
@@ -22,7 +23,21 @@ RUN test "$PHP" != "7.0" || pecl install xdebug
 RUN docker-php-ext-enable xdebug
 
 # install dependencies and cleanup (needs to be one step, as else it will cache in the layer)
-RUN apt-get update -y \
+RUN test "$PHP" = "7.4" || apt-get update -y \
+    && DEBIAN_FRONTEND=noninteractive apt-get install -yf \
+        $RUNTIME_PACKAGE_DEPS \
+        $BUILD_PACKAGE_DEPS \
+    && docker-php-ext-configure gd \
+    && docker-php-ext-install -j$(nproc) $PHP_EXT_DEPS \
+    && pecl install $PECL_DEPS \
+    && docker-php-ext-enable $PECL_DEPS \
+    && docker-php-source delete \
+    && apt-get clean \
+    && apt-get autoremove -y \
+    && apt-get purge -y --auto-remove $BUILD_PACKAGE_DEPS \
+    && rm -rf /var/lib/apt/lists/*
+
+RUN test "$PHP" != "7.4" || apt-get update -y \
     && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
         $RUNTIME_PACKAGE_DEPS \
         $BUILD_PACKAGE_DEPS \