diff --git a/git-crypt/Dockerfile b/git-crypt/Dockerfile
index 98a8af8..f6ca84b 100644
--- a/git-crypt/Dockerfile
+++ b/git-crypt/Dockerfile
@@ -2,7 +2,7 @@
 # Based on the outdated dockerfile at https://github.com/lukebond/docker-git-crypt
 #
 
-FROM alpine:3.9@sha256:28ef97b8686a0b5399129e9b763d5b7e5ff03576aa5580d6f4182a49c5fe1913
+FROM alpine:3.15@sha256:21a3deaa0d32a8057914f36584b5288d2e5ecc984380bc0118285c70fa8c9300
 
 ENV GIT_CRYPT_VERSION 0.6.0
 ENV GIT_CRYPT_CHECKSUM 777c0c7aadbbc758b69aff1339ca61697011ef7b92f1d1ee9518a8ee7702bb78