diff --git a/port/win/win_logger.cc b/port/win/win_logger.cc
index e89c1af6d..9d6203cc4 100644
--- a/port/win/win_logger.cc
+++ b/port/win/win_logger.cc
@@ -132,7 +132,7 @@ void WinLogger::Logv(const char* format, va_list ap) {
     }
 
     flush_pending_ = true;
-    assert(bytesWritten == write_size);
+    assert((bytesWritten == write_size) || (ret == FALSE));
     if (bytesWritten > 0) {
       log_size_ += write_size;
     }