diff --git a/Dockerfile b/Dockerfile
index 3a95f41..6246949 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -3,4 +3,4 @@
 
 FROM registry.leenooks.net/leenooks/php:8.0-fpm-latest
 
-RUN docker-php-ext-install -j$(nproc) sockets pcntl
+RUN CFLAGS="$CFLAGS -D_GNU_SOURCE" docker-php-ext-install -j$(nproc) sockets pcntl