diff --git a/internal/test/vm/Dockerfile b/internal/test/vm/Dockerfile
index e45f8d01c..defea0bfe 100644
--- a/internal/test/vm/Dockerfile
+++ b/internal/test/vm/Dockerfile
@@ -1,4 +1,4 @@
-FROM alpine:3.20
+FROM alpine:3.22@sha256:4b7ce07002c69e8f3d704a9c5d6fd3053be500b7f1c69fc0d80990c2ad8dd412
 
 # this is the toplevel Makefile target to be invoked
 # see the contents of 'startup.sh' at the end of this file