diff --git a/dune-project b/dune-project
index e54c77c..eba840f 100644
--- a/dune-project
+++ b/dune-project
@@ -17,6 +17,7 @@
     (logs (>= 0.6))
     (base (>= v0.12))
     (stdio (>= v0.12))
+    (ppx_let (>= v0.12))
     (odig (>= 0.0.4))
     (odoc (>= 1.5))
     (sqlite3 (>= 4.4))
diff --git a/odoc2docset.opam b/odoc2docset.opam
index cb9e127..08f8278 100644
--- a/odoc2docset.opam
+++ b/odoc2docset.opam
@@ -21,6 +21,7 @@ depends: [
   "logs" {>= "0.6"}
   "base" {>= "v0.12"}
   "stdio" {>= "v0.12"}
+  "ppx_let" {>= "v0.12"}
   "odig" {>= "0.0.4"}
   "odoc" {>= "1.5"}
   "sqlite3" {>= "4.4"}