diff --git a/modules/restricted-guests/synapse/Dockerfile b/modules/restricted-guests/synapse/Dockerfile
index e98bbddd61..dc39a088c6 100644
--- a/modules/restricted-guests/synapse/Dockerfile
+++ b/modules/restricted-guests/synapse/Dockerfile
@@ -1,8 +1,12 @@
 ARG DEBIAN_VERSION_NUMERIC=12
+
+# Now copy it into our base image.
+FROM gcr.io/distroless/base-nossl-debian${DEBIAN_VERSION_NUMERIC}:debug AS build
+
 FROM gcr.io/distroless/base-nossl-debian${DEBIAN_VERSION_NUMERIC}
 
 WORKDIR /src
 COPY synapse_guest_module /src/synapse_guest_module
-COPY /bin/cp /bin/cp
+COPY --from=build /busybox/cp /bin/cp
 
 CMD ["cp", "-r", "/src/synapse_guest_module", "/modules"]