diff --git a/sim_serial.c b/sim_serial.c
index d9b5fdb2..9cdd78ae 100644
--- a/sim_serial.c
+++ b/sim_serial.c
@@ -1324,10 +1324,14 @@ int written;
 written = write (port, (void *) buffer, (size_t) count);    /* write the buffer to the serial port */
 
 if (written == -1) {
-    if (errno != EAGAIN)                                    /* unexpected error? */
-        sim_error_serial ("write", errno);                  /* report it */
-    else
+    if (errno == EWOULDBLOCK)
         written = 0;                                        /* not an error, but nothing written */
+#if defined(EAGAIN)
+    else if (errno == EAGAIN)
+        written = 0;                                        /* not an error, but nothing written */
+#endif
+    else                                                    /* unexpected error? */
+        sim_error_serial ("write", errno);                  /* report it */
     }
 
 return (int32) written;                                     /* return number of characters written */