diff --git a/src/UnitTests/NmeaParser.Tests.NET45/NmeaParser.Tests.NET45.csproj b/src/UnitTests/NmeaParser.Tests.NET45/NmeaParser.Tests.NET45.csproj
index 8d18743..c3d4368 100644
--- a/src/UnitTests/NmeaParser.Tests.NET45/NmeaParser.Tests.NET45.csproj
+++ b/src/UnitTests/NmeaParser.Tests.NET45/NmeaParser.Tests.NET45.csproj
@@ -19,6 +19,8 @@
     <TestProjectType>UnitTest</TestProjectType>
     <NuGetPackageImportStamp>
     </NuGetPackageImportStamp>
+	<LangVersion>8.0</LangVersion>
+	<Nullable>enable</Nullable>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <DebugSymbols>true</DebugSymbols>
diff --git a/src/UnitTests/NmeaParser.Tests.UWP/NmeaParser.Tests.UWP.csproj b/src/UnitTests/NmeaParser.Tests.UWP/NmeaParser.Tests.UWP.csproj
index 95e231d..a115610 100644
--- a/src/UnitTests/NmeaParser.Tests.UWP/NmeaParser.Tests.UWP.csproj
+++ b/src/UnitTests/NmeaParser.Tests.UWP/NmeaParser.Tests.UWP.csproj
@@ -13,12 +13,14 @@
     <TargetPlatformIdentifier>UAP</TargetPlatformIdentifier>
     <TargetPlatformVersion>10.0.17763.0</TargetPlatformVersion>
     <TargetPlatformMinVersion>10.0.16299.0</TargetPlatformMinVersion>
-    <MinimumVisualStudioVersion>14</MinimumVisualStudioVersion>
+    <MinimumVisualStudioVersion>16</MinimumVisualStudioVersion>
     <FileAlignment>512</FileAlignment>
     <ProjectTypeGuids>{A5A43C5B-DE2A-4C0C-9213-0A381AF9435A};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
     <PackageCertificateKeyFile>NmeaParser.Tests.UWP_TemporaryKey.pfx</PackageCertificateKeyFile>
     <UnitTestPlatformVersion Condition="'$(UnitTestPlatformVersion)' == ''">$(VisualStudioVersion)</UnitTestPlatformVersion>
     <PackageCertificateThumbprint>D07B149B4E796AB0184B2E2FC9DDC1A2F5CA5A7E</PackageCertificateThumbprint>
+	<LangVersion>8.0</LangVersion>
+	<Nullable>enable</Nullable>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|x86'">
     <DebugSymbols>true</DebugSymbols>
diff --git a/src/UnitTests/NmeaParser.Tests.UWP/UnitTestApp.xaml.cs b/src/UnitTests/NmeaParser.Tests.UWP/UnitTestApp.xaml.cs
index bbcb58c..4d18550 100644
--- a/src/UnitTests/NmeaParser.Tests.UWP/UnitTestApp.xaml.cs
+++ b/src/UnitTests/NmeaParser.Tests.UWP/UnitTestApp.xaml.cs
@@ -47,7 +47,7 @@ namespace NmeaParser.Tests.UWP
             }
 #endif
 
-            Frame rootFrame = Window.Current.Content as Frame;
+            Frame? rootFrame = Window.Current?.Content as Frame;
 
             // Do not repeat app initialization when the Window already has content,
             // just ensure that the window is active
@@ -64,13 +64,15 @@ namespace NmeaParser.Tests.UWP
                 }
 
                 // Place the frame in the current Window
-                Window.Current.Content = rootFrame;
+                if (Window.Current != null)
+                    Window.Current.Content = rootFrame;
             }
             
             Microsoft.VisualStudio.TestPlatform.TestExecutor.UnitTestClient.CreateDefaultUI();
 
             // Ensure the current window is active
-            Window.Current.Activate();
+            if (Window.Current != null)
+                Window.Current.Activate();
 
             Microsoft.VisualStudio.TestPlatform.TestExecutor.UnitTestClient.Run(e.Arguments);
         }
diff --git a/src/UnitTests/NmeaParser.Tests/DeviceTests.cs b/src/UnitTests/NmeaParser.Tests/DeviceTests.cs
index d7702d3..d4a61f7 100644
--- a/src/UnitTests/NmeaParser.Tests/DeviceTests.cs
+++ b/src/UnitTests/NmeaParser.Tests/DeviceTests.cs
@@ -26,7 +26,7 @@ namespace NmeaParser.Tests
 				{
 					Assert.IsTrue(e.IsMultipart, "IsMultiPart");
 					Assert.IsInstanceOfType(e.Message, typeof(NmeaParser.Nmea.Gsv));
-					var msg = e.Message as NmeaParser.Nmea.Gsv;
+					var msg = (NmeaParser.Nmea.Gsv)e.Message;
 					if (msg.TotalMessages == msg.MessageNumber)
 					{
 						Assert.IsNotNull(e.MessageParts);
@@ -67,7 +67,7 @@ $GAGSV,4,4,14,19,82,349,40,1,44,220,40,4,24,314,38*5F";
                 {
                     Assert.IsTrue(e.IsMultipart, "IsMultiPart");
                     Assert.IsInstanceOfType(e.Message, typeof(NmeaParser.Nmea.Gsv));
-                    var msg = e.Message as NmeaParser.Nmea.Gsv;
+                    var msg = (NmeaParser.Nmea.Gsv)e.Message;
                     if (msg.TotalMessages == msg.MessageNumber)
                     {
                         Assert.IsNotNull(e.MessageParts);