diff --git a/portainer-compose.yml b/portainer-compose.yml
index 9730e8e..7e6c5fd 100644
--- a/portainer-compose.yml
+++ b/portainer-compose.yml
@@ -52,6 +52,13 @@ services:
       - edge
     cap_add:
       - IPC_LOCK
+    # Newer vault:latest mlocks more than docker's default 64KB memlock ulimit;
+    # without this it crash-loops with "Failed to lock memory: cannot allocate
+    # memory" despite IPC_LOCK being granted.
+    ulimits:
+      memlock:
+        soft: -1
+        hard: -1
     environment:
       - VAULT_ADDR=http://0.0.0.0:8200
     volumes: