diff --git a/build/docker/Dockerfile.monolith b/build/docker/Dockerfile.monolith
index bb02934cd5..a7e564ef82 100644
--- a/build/docker/Dockerfile.monolith
+++ b/build/docker/Dockerfile.monolith
@@ -11,7 +11,7 @@ RUN go build -trimpath -o bin/ ./cmd/dendrite-monolith-server
 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 (Monolith)"
 LABEL org.opencontainers.image.description="Next-generation Matrix homeserver written in Go"
 LABEL org.opencontainers.image.source="https://github.com/matrix-org/dendrite"