diff --git a/tensorboard/defs/web.bzl b/tensorboard/defs/web.bzl
index 0605a74361..9be5cd533c 100644
--- a/tensorboard/defs/web.bzl
+++ b/tensorboard/defs/web.bzl
@@ -203,11 +203,13 @@ def _tf_web_library(ctx):
     # If a rule exists purely to export other build rules, then it's
     # appropriate for the exported sources to be included in the
     # development web server.
-    devserver_manifests = depset(order="postorder")
     export_deps = unfurl(ctx.attr.exports)
-    for dep in export_deps:
-      devserver_manifests += dep.webfiles.manifests
-    devserver_manifests = manifests + devserver_manifests
+    devserver_manifests = depset(
+        order = "postorder",
+        transitive = (
+            [manifests] + [dep.webfiles.manifests for dep in export_deps]
+        ),
+    )
   params = struct(
       label=str(ctx.label),
       bind="localhost:6006",