diff --git a/release/Dockerfile b/release/Dockerfile
index 466cb8d..47f092c 100644
--- a/release/Dockerfile
+++ b/release/Dockerfile
@@ -1,5 +1,5 @@
 FROM ocaml/opam:alpine-ocaml-4.14
-RUN sudo apk add libev-dev openssl-dev
+RUN sudo apk add libev-dev openssl-dev libffi-dev
 RUN sudo apk add openssl-libs-static
 WORKDIR slipshow/