diff --git a/cohttp-async.opam b/cohttp-async.opam
index 349faf3a7..0023b4257 100644
--- a/cohttp-async.opam
+++ b/cohttp-async.opam
@@ -31,7 +31,7 @@ depends: [
   "async_kernel" {>= "v0.14.0"}
   "async_unix" {>= "v0.14.0"}
   "async" {>= "v0.14.0"}
-  "base" {>= "v0.11.0"}
+  "base" {>= "v0.11.0" & < "v0.16.0"}
   "core" {with-test}
   "core_unix" {>= "v0.14.0"}
   "conduit-async" {>= "1.2.0"}
diff --git a/dune-project b/dune-project
index 948b48a3b..f9199a8ca 100644
--- a/dune-project
+++ b/dune-project
@@ -180,7 +180,9 @@ should also be fine under Windows too.
   (async
    (>= v0.14.0))
   (base
-   (>= v0.11.0))
+   (and
+    (>= v0.11.0)
+    (< v0.16.0)))
   (core :with-test)
   (core_unix
    (>= v0.14.0))