diff --git a/upb/port/BUILD b/upb/port/BUILD
index dc1c343c7a01..fe20c085e5cd 100644
--- a/upb/port/BUILD
+++ b/upb/port/BUILD
@@ -14,7 +14,15 @@ cc_library(
         "vsnprintf_compat.h",
     ],
     copts = UPB_DEFAULT_COPTS,
-    textual_hdrs = [":inc"],
+    textual_hdrs = [
+        # We must list the headers explicitly here instead of relying on the
+        # :inc filegroup below. gRPC auto-generates various build configs from
+        # the Bazel graph, and this logic does not know how to handle
+        # filegroups. We might be able to replace these headers with just
+        # ":inc" after gRPC starts using upb's CMake build.
+        "def.inc",
+        "undef.inc",
+    ],
     visibility = ["//visibility:public"],
 )