diff --git a/aos/uuid_collision_test.cc b/aos/uuid_collision_test.cc
new file mode 100644
index 0000000..f06f6de
--- /dev/null
+++ b/aos/uuid_collision_test.cc
@@ -0,0 +1,28 @@
+#include <set>
+#include <unordered_set>
+
+#include "glog/logging.h"
+#include "gtest/gtest.h"
+
+#include "aos/uuid.h"
+
+namespace aos {
+namespace testing {
+
+// Tests that modest numbers of UUID::Random() calls cannot create UUID
+// collisions (to test that we have not *completely* messed up the random number
+// generation).
+TEST(UUIDTest, CollisionTest) {
+  std::set<UUID> uuids;
+  // When we only had ~32 bits of randomness in our UUIDs, we could generate
+  // issues with only ~sqrt(2 ** 32) (aka 2 ** 16) UUIDs.
+  // Just go up to 2 ** 22, since too much longer just makes this test take
+  // obnoxiously long.
+  for (size_t ii = 0; ii < (1UL << 22); ++ii) {
+    UUID uuid = UUID::Random();
+    ASSERT_FALSE(uuids.count(uuid) > 0) << ii;
+    uuids.insert(uuid);
+  }
+}
+}  // namespace testing
+}  // namespace aos