diff --git a/src/libraries/System.Private.CoreLib/src/System/IO/FileStream.cs b/src/libraries/System.Private.CoreLib/src/System/IO/FileStream.cs
index a7f6aaecb5b85..90234962a5838 100644
--- a/src/libraries/System.Private.CoreLib/src/System/IO/FileStream.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/IO/FileStream.cs
@@ -14,7 +14,7 @@ public class FileStream : Stream
     {
         internal const int DefaultBufferSize = 4096;
         internal const FileShare DefaultShare = FileShare.Read;
-        private const bool DefaultIsAsync = false;
+        private const bool DefaultIsAsync = true;
 
         private readonly FileStreamStrategy _strategy;