diff --git a/Dockerfile b/Dockerfile
index 9c84f27..0d64562 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,7 +1,7 @@
 FROM python:3.7-alpine
 
 RUN apk add --no-cache --virtual .build-deps \
-        git make gcc musl-dev \
+        git make gcc musl-dev a2x \
 
     # Install deps
     && pip install snakeoil \