diff --git a/stable/alpine-slim/Dockerfile b/stable/alpine-slim/Dockerfile
index 65bd5449..af03749c 100644
--- a/stable/alpine-slim/Dockerfile
+++ b/stable/alpine-slim/Dockerfile
@@ -3,7 +3,7 @@
 #
 # PLEASE DO NOT EDIT IT DIRECTLY.
 #
-FROM alpine:3.20
+FROM alpine:3.21
 
 LABEL maintainer="NGINX Docker Maintainers <docker-maint@nginx.com>"
 
diff --git a/update.sh b/update.sh
index 08744e96..7df556d6 100755
--- a/update.sh
+++ b/update.sh
@@ -56,7 +56,7 @@ declare -A debian=(
 
 declare -A alpine=(
     [mainline]='3.21'
-    [stable]='3.20'
+    [stable]='3.21'
 )
 
 # When we bump njs version in a stable release we don't move the tag in the