diff --git a/Dockerfile b/Dockerfile
index 0c037e1..85a6c96 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -25,7 +25,7 @@ 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=5.1.19
+ARG APCU_VERSION=5.1.20
 RUN set -eux; \
 	apk add --no-cache --virtual .build-deps \
 		$PHPIZE_DEPS \