diff --git a/lib/pure/streams.nim b/lib/pure/streams.nim
index 438b48beba..69f6739903 100644
--- a/lib/pure/streams.nim
+++ b/lib/pure/streams.nim
@@ -411,12 +411,12 @@ when not defined(js):
     result.writeDataImpl = fsWriteData
     result.flushImpl = fsFlush
 
-  proc newFileStream*(filename: string, mode: FileMode = fmRead): FileStream =
+  proc newFileStream*(filename: string, mode: FileMode = fmRead, bufSize: int = -1): FileStream =
     ## creates a new stream from the file named `filename` with the mode `mode`.
     ## If the file cannot be opened, nil is returned. See the `system
     ## <system.html>`_ module for a list of available FileMode enums.
     var f: File
-    if open(f, filename, mode): result = newFileStream(f)
+    if open(f, filename, mode, bufSize): result = newFileStream(f)
 
 
 when true: