Build error: Uninterpreted extension cenum

[basus]

I'm getting the following error when trying to build the current master:

Finished, 1 target (0 cached) in 00:00:00.
+ /home/basus/.opam/4.03.0/bin/ocamlfind ocamlc -c -w @5+8@11@12-40 -short-paths -g -annot -bin-annot -thread -thread -package yo
json -package threads -package tcpip -package str -package sedlex -package ppx_import -package ocamlgraph -package menhirLib -pac
kage ipaddr -package cstruct -package core -package compiler-libs.common -package base64 -package ppx_deriving,ppx_deriving.eq,pp
x_deriving.enum,ppx_deriving.show,ppx_jane -I lib -o lib/Frenetic_OpenFlow0x04.cmo lib/Frenetic_OpenFlow0x04.ml
File "lib/Frenetic_OpenFlow0x04.ml", line 748, characters 5-10:
Uninterpreted extension 'cenum'.
Command exited with code 2.
Compilation unsuccessful after building 95 targets (0 cached) in 00:00:28.
E: Failure("Command ''/home/basus/.opam/4.03.0/bin/ocamlbuild' lib/frenetic.cma lib/frenetic.cmxa lib/frenetic.a lib/frenetic.cmx
s ppx/ppx.cma ppx/ppx.cmxa ppx/ppx.a ppx/ppx.cmxs ppx/ppx.native async/async.cma async/async.cmxa async/async.a async/async.cmxs 
frenetic/frenetic.native frenetic/openflow.native bench/src/Main.native -use-ocamlfind -package ppx_deriving,ppx_deriving.eq,ppx_
deriving.enum,ppx_deriving.show,ppx_jane -use-menhir -cflags -w,@5+8@11@12-40,-short-paths -tag debug -j 4' terminated with error
 code 10")
make: *** [Makefile:16: build] Error 1

Looks like there is a ppx extension called using %%cenum that isn't in my environment. I couldn't find it in opam or with some quick Googling.