diff --git a/src/unix/os390.c b/src/unix/os390.c
index dce169b9..458e7310 100644
--- a/src/unix/os390.c
+++ b/src/unix/os390.c
@@ -887,12 +887,13 @@ void uv__io_poll(uv_loop_t* loop, int timeout) {
     if (nfds == 0) {
       assert(timeout != -1);
 
-      if (timeout > 0) {
-        timeout = real_timeout - timeout;
-        continue;
-      }
+      if (timeout == 0)
+        return;
 
-      return;
+      /* We may have been inside the system call for longer than |timeout|
+       * milliseconds so we need to update the timestamp to avoid drift.
+       */
+      goto update_timeout;
     }
 
     if (nfds == -1) {