diff --git a/.bazelci/presubmit.yml b/.bazelci/presubmit.yml
index b29a991..cb949a0 100644
--- a/.bazelci/presubmit.yml
+++ b/.bazelci/presubmit.yml
@@ -1,8 +1,5 @@
 ---
 tasks:
-  ubuntu1804:
-    build_targets:
-    - "//..."
   ubuntu2004:
     build_targets:
     - "//..."
@@ -12,3 +9,11 @@
   windows:
     build_targets:
     - "//..."
+  ubuntu2004:
+    # No need to check bzlmod on every platform. This repository only holds
+    # constants and has no per-platform behavior.
+    name: check_bzlmod
+    build_targets:
+    - "//..."
+    build_flags:
+    - "--experimental_enable_bzlmod"
diff --git a/MODULE.bazel b/MODULE.bazel
new file mode 100644
index 0000000..e4f4cfd
--- /dev/null
+++ b/MODULE.bazel
@@ -0,0 +1,5 @@
+module(
+    name = "platforms",
+    version = "0.0.6",  # keep in sync with version.bzl
+    compatibility_level = 1,
+)