diff --git a/t/Dockerfile b/t/Dockerfile
index 74a4407..ea972d7 100644
--- a/t/Dockerfile
+++ b/t/Dockerfile
@@ -5,7 +5,7 @@ FROM docker.mgm.sipwise.com/sipwise-buster:latest
 # is updated with the current date. It will force refresh of all
 # of the base images and things like `apt-get update` won't be using
 # old cached versions when the Dockerfile is built.
-ENV REFRESHED_AT 2023-05-24
+ENV REFRESHED_AT 2023-12-05
 
 COPY t/sources.list.d/builddeps.list /etc/apt/sources.list.d/
 COPY t/sources.list.d/preferences /etc/apt/preferences.d/
@@ -13,6 +13,7 @@ COPY t/sources.list.d/preferences /etc/apt/preferences.d/
 RUN apt-get update && \
   apt-get install --assume-yes \
         curl \
+        mocha \
         nodejs \
         npm \
         && \