diff --git a/docker-compose.yml b/docker-compose.yml
index 16a07cd..e4ef9ca 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -50,8 +50,11 @@ services:
       - GF_AUTH_ANONYMOUS_ORG_ROLE=Viewer
       - GF_AUTH_ANONYMOUS_HIDE_VERSION=true
       # SQL-computed labels (patterns, raw table, SLA day grouping) use SQLite's
-      # 'localtime', which resolves to this container's timezone.
+      # 'localtime', which resolves to this container's timezone. Grafana strips
+      # host env vars from plugin processes by default, so TZ must be forwarded
+      # explicitly to the sqlite datasource.
       - TZ=${TZ:-Etc/UTC}
+      - GF_PLUGINS_FORWARD_HOST_ENV_VARS=frser-sqlite-datasource
     volumes:
       # :ro because any Grafana viewer (incl. anonymous) can send arbitrary SQL
       # to the datasource API; the mount and mode=ro keep that harmless.