diff --git a/System.IO.FileSystem.UnitTests/System.IO.FileSystem.UnitTests.nfproj b/System.IO.FileSystem.UnitTests/System.IO.FileSystem.UnitTests.nfproj
index 18cb0a7..8f41499 100644
--- a/System.IO.FileSystem.UnitTests/System.IO.FileSystem.UnitTests.nfproj
+++ b/System.IO.FileSystem.UnitTests/System.IO.FileSystem.UnitTests.nfproj
@@ -61,7 +61,7 @@
       <HintPath>..\packages\nanoFramework.TestFramework.4.0.0-preview.58\lib\netnano1.0\nanoFramework.UnitTestLauncher.exe</HintPath>
     </Reference>
     <Reference Include="System.IO.Streams, Version=2.0.0.0, Culture=neutral, PublicKeyToken=c07d481e9758c731">
-      <HintPath>..\packages\nanoFramework.System.IO.Streams.2.0.0-preview.18\lib\netnano1.0\System.IO.Streams.dll</HintPath>
+      <HintPath>..\packages\nanoFramework.System.IO.Streams.2.0.0-preview.21\lib\netnano1.0\System.IO.Streams.dll</HintPath>
     </Reference>
   </ItemGroup>
   <ItemGroup>
diff --git a/System.IO.FileSystem.UnitTests/packages.config b/System.IO.FileSystem.UnitTests/packages.config
index be0f3ab..94d4f12 100644
--- a/System.IO.FileSystem.UnitTests/packages.config
+++ b/System.IO.FileSystem.UnitTests/packages.config
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
   <package id="nanoFramework.CoreLibrary" version="2.0.0-preview.52" targetFramework="netnano1.0" />
-  <package id="nanoFramework.System.IO.Streams" version="2.0.0-preview.18" targetFramework="netnano1.0" />
+  <package id="nanoFramework.System.IO.Streams" version="2.0.0-preview.21" targetFramework="netnano1.0" />
   <package id="nanoFramework.System.Text" version="2.0.0-preview.18" targetFramework="netnano1.0" />
   <package id="nanoFramework.TestFramework" version="4.0.0-preview.58" targetFramework="netnano1.0" developmentDependency="true" />
 </packages>
\ No newline at end of file
diff --git a/System.IO.FileSystem.UnitTests/packages.lock.json b/System.IO.FileSystem.UnitTests/packages.lock.json
index 1970450..a35e189 100644
--- a/System.IO.FileSystem.UnitTests/packages.lock.json
+++ b/System.IO.FileSystem.UnitTests/packages.lock.json
@@ -10,9 +10,9 @@
       },
       "nanoFramework.System.IO.Streams": {
         "type": "Direct",
-        "requested": "[2.0.0-preview.18, 2.0.0-preview.18]",
-        "resolved": "2.0.0-preview.18",
-        "contentHash": "X6Zv6eYRWqSY1eu7S7SwfIoFtFQfc8Rrl7CJN8dxuiry0K4SioSjuRFvnGerTnCWPEXy1gXGbbLRBVkYscw9fg=="
+        "requested": "[2.0.0-preview.21, 2.0.0-preview.21]",
+        "resolved": "2.0.0-preview.21",
+        "contentHash": "wsgKxwjG/QWIgIi/6zPs9M5u1g8digdOHOkUXweij0jHg96yjfCaN6907XElq9zT79QDomJWKMFGSdGqJAkm4Q=="
       },
       "nanoFramework.System.Text": {
         "type": "Direct",
diff --git a/System.IO.FileSystem/System.IO.FileSystem.nfproj b/System.IO.FileSystem/System.IO.FileSystem.nfproj
index 2c1d6e1..9f4225c 100644
--- a/System.IO.FileSystem/System.IO.FileSystem.nfproj
+++ b/System.IO.FileSystem/System.IO.FileSystem.nfproj
@@ -86,7 +86,7 @@
       <HintPath>..\packages\nanoFramework.System.Text.2.0.0-preview.18\lib\netnano1.0\nanoFramework.System.Text.dll</HintPath>
     </Reference>
     <Reference Include="System.IO.Streams, Version=2.0.0.0, Culture=neutral, PublicKeyToken=c07d481e9758c731">
-      <HintPath>..\packages\nanoFramework.System.IO.Streams.2.0.0-preview.18\lib\netnano1.0\System.IO.Streams.dll</HintPath>
+      <HintPath>..\packages\nanoFramework.System.IO.Streams.2.0.0-preview.21\lib\netnano1.0\System.IO.Streams.dll</HintPath>
     </Reference>
   </ItemGroup>
   <ProjectExtensions>
diff --git a/System.IO.FileSystem/packages.config b/System.IO.FileSystem/packages.config
index b5dc277..3171e23 100644
--- a/System.IO.FileSystem/packages.config
+++ b/System.IO.FileSystem/packages.config
@@ -2,7 +2,7 @@
 <packages>
   <package id="nanoFramework.CoreLibrary" version="2.0.0-preview.52" targetFramework="netnano1.0" />
   <package id="nanoFramework.Runtime.Events" version="2.0.0-preview.13" targetFramework="netnano1.0" />
-  <package id="nanoFramework.System.IO.Streams" version="2.0.0-preview.18" targetFramework="netnano1.0" />
+  <package id="nanoFramework.System.IO.Streams" version="2.0.0-preview.21" targetFramework="netnano1.0" />
   <package id="nanoFramework.System.Text" version="2.0.0-preview.18" targetFramework="netnano1.0" />
   <package id="Nerdbank.GitVersioning" version="3.9.50" developmentDependency="true" targetFramework="netnano1.0" />
 </packages>
\ No newline at end of file
diff --git a/System.IO.FileSystem/packages.lock.json b/System.IO.FileSystem/packages.lock.json
index f8d893d..548f32b 100644
--- a/System.IO.FileSystem/packages.lock.json
+++ b/System.IO.FileSystem/packages.lock.json
@@ -16,9 +16,9 @@
       },
       "nanoFramework.System.IO.Streams": {
         "type": "Direct",
-        "requested": "[2.0.0-preview.18, 2.0.0-preview.18]",
-        "resolved": "2.0.0-preview.18",
-        "contentHash": "X6Zv6eYRWqSY1eu7S7SwfIoFtFQfc8Rrl7CJN8dxuiry0K4SioSjuRFvnGerTnCWPEXy1gXGbbLRBVkYscw9fg=="
+        "requested": "[2.0.0-preview.21, 2.0.0-preview.21]",
+        "resolved": "2.0.0-preview.21",
+        "contentHash": "wsgKxwjG/QWIgIi/6zPs9M5u1g8digdOHOkUXweij0jHg96yjfCaN6907XElq9zT79QDomJWKMFGSdGqJAkm4Q=="
       },
       "nanoFramework.System.Text": {
         "type": "Direct",
diff --git a/nanoFramework.System.IO.FileSystem.nuspec b/nanoFramework.System.IO.FileSystem.nuspec
index e678e22..d0111ad 100644
--- a/nanoFramework.System.IO.FileSystem.nuspec
+++ b/nanoFramework.System.IO.FileSystem.nuspec
@@ -22,7 +22,7 @@ This package requires a target with System.IO.FileSystem v$nativeVersion$ (check
       <group targetFramework=".NETnanoFramework1.0">
         <dependency id="nanoFramework.CoreLibrary" version="2.0.0-preview.52" />
         <dependency id="nanoFramework.Runtime.Events" version="2.0.0-preview.13" />
-        <dependency id="nanoFramework.System.IO.Streams" version="2.0.0-preview.18" />
+        <dependency id="nanoFramework.System.IO.Streams" version="2.0.0-preview.21" />
         <dependency id="nanoFramework.System.Text" version="2.0.0-preview.18" />
       </group>
     </dependencies>