diff --git a/driver_library/src/ethosu_stub.cpp b/driver_library/src/ethosu_stub.cpp
index 9dfc029..510007f 100644
--- a/driver_library/src/ethosu_stub.cpp
+++ b/driver_library/src/ethosu_stub.cpp
@@ -76,8 +76,9 @@
     }
 }
 
-int epoll(struct pollfd *, nfds_t, int timeout) {
-    sleep(timeout / 2);
+int epoll(struct pollfd *, nfds_t, int timeout_ms) {
+    int t = 1000 * timeout_ms / 2;
+    usleep(t);
     return 1;
 }
 } // namespace EthosU