diff --git a/build/docker/Dockerfile.polylith b/build/docker/Dockerfile.polylith
index 166ea99cb0..25ab122e24 100644
--- a/build/docker/Dockerfile.polylith
+++ b/build/docker/Dockerfile.polylith
@@ -11,7 +11,7 @@ RUN go build -trimpath -o bin/ ./cmd/dendrite-polylith-multi
 RUN go build -trimpath -o bin/ ./cmd/create-account
 RUN go build -trimpath -o bin/ ./cmd/generate-keys
 
-FROM alpine:latest
+FROM alpine:3.18.3
 LABEL org.opencontainers.image.title="Dendrite (Polylith)"
 LABEL org.opencontainers.image.description="Next-generation Matrix homeserver written in Go"
 LABEL org.opencontainers.image.source="https://github.com/matrix-org/dendrite"