diff --git a/os/test_urandom.py b/os/test_urandom.py
new file mode 100644
index 00000000..53b34f06
--- /dev/null
+++ b/os/test_urandom.py
@@ -0,0 +1,4 @@
+import os
+
+r = os.urandom(10)
+assert len(r) == 10