diff --git a/dune-project b/dune-project
index 0b782996..41ba5911 100644
--- a/dune-project
+++ b/dune-project
@@ -37,8 +37,8 @@
   (alcotest :with-test)
   (pbrt
    (and
-    (>= 3.0)
-    (< 4.0)))
+    (>= 4.0)
+    (< 5.0)))
   (ocaml-lsp-server :with-dev-setup)
   (ocamlformat
    (and
diff --git a/opentelemetry.opam b/opentelemetry.opam
index cdbdcf2e..7e3128d9 100644
--- a/opentelemetry.opam
+++ b/opentelemetry.opam
@@ -21,7 +21,7 @@ depends: [
   "thread-local-storage" {>= "0.2" & < "0.3"}
   "odoc" {with-doc}
   "alcotest" {with-test}
-  "pbrt" {>= "3.0" & < "4.0"}
+  "pbrt" {>= "4.0" & < "5.0"}
   "ocaml-lsp-server" {with-dev-setup}
   "ocamlformat" {with-dev-setup & >= "0.27" & < "0.28"}
   "mtime" {>= "1.4"}