diff --git a/Dockerfile b/Dockerfile
index 9e849bd..e244d3e 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -4,7 +4,7 @@
 
 
 # https://docs.docker.com/engine/reference/builder/#understand-how-arg-and-from-interact
-ARG PHP_VERSION=8.0
+ARG PHP_VERSION=8.1
 ARG CADDY_VERSION=2
 
 # "php" stage
@@ -24,7 +24,7 @@ RUN apk add --no-cache \
 # see https://github.com/docker-library/php/issues/240#issuecomment-763112749
 ENV LD_PRELOAD /usr/lib/preloadable_libiconv.so
 
-ARG APCU_VERSION=5.1.20
+ARG APCU_VERSION=5.1.21
 RUN set -eux; \
 	apk add --no-cache --virtual .build-deps \
 		$PHPIZE_DEPS \