diff --git a/core/admin/Dockerfile b/core/admin/Dockerfile
index 08de0e88..2e637206 100644
--- a/core/admin/Dockerfile
+++ b/core/admin/Dockerfile
@@ -7,7 +7,7 @@ COPY requirements-prod.txt requirements.txt
 RUN apk add --no-cache openssl \
  && apk add --no-cache --virtual build-dep openssl-dev libffi-dev python-dev build-base \
  && pip install -r requirements.txt \
- && apk del build-dep
+ && apk del --no-cache build-dep
 
 COPY mailu ./mailu
 COPY migrations ./migrations