diff --git a/SafeExamBrowser.Client.UnitTests/Notifications/AboutNotificationControllerTests.cs b/SafeExamBrowser.Client.UnitTests/Notifications/AboutNotificationControllerTests.cs
index 1abfda99..f1ad737d 100644
--- a/SafeExamBrowser.Client.UnitTests/Notifications/AboutNotificationControllerTests.cs
+++ b/SafeExamBrowser.Client.UnitTests/Notifications/AboutNotificationControllerTests.cs
@@ -6,6 +6,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
+using System.IO.Packaging;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Moq;
 using SafeExamBrowser.Client.Notifications;
@@ -29,6 +30,9 @@ namespace SafeExamBrowser.Client.UnitTests.Notifications
 			appConfig = new Mock<AppConfig>();
 			text = new Mock<IText>();
 			uiFactory = new Mock<IUserInterfaceFactory>();
+
+			// Ensure that the pack scheme is known before executing the unit tests, see https://stackoverflow.com/a/6005606
+			_ = PackUriHelper.UriSchemePack;
 		}
 
 		[TestMethod]
diff --git a/SafeExamBrowser.Client.UnitTests/Notifications/LogNotificationControllerTests.cs b/SafeExamBrowser.Client.UnitTests/Notifications/LogNotificationControllerTests.cs
index 4d2c382a..bec16f23 100644
--- a/SafeExamBrowser.Client.UnitTests/Notifications/LogNotificationControllerTests.cs
+++ b/SafeExamBrowser.Client.UnitTests/Notifications/LogNotificationControllerTests.cs
@@ -6,6 +6,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
+using System.IO.Packaging;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Moq;
 using SafeExamBrowser.Client.Notifications;
@@ -29,6 +30,9 @@ namespace SafeExamBrowser.Client.UnitTests.Notifications
 			logger = new Mock<ILogger>();
 			text = new Mock<IText>();
 			uiFactory = new Mock<IUserInterfaceFactory>();
+
+			// Ensure that the pack scheme is known before executing the unit tests, see https://stackoverflow.com/a/6005606
+			_ = PackUriHelper.UriSchemePack;
 		}
 
 		[TestMethod]
diff --git a/SafeExamBrowser.Client.UnitTests/SafeExamBrowser.Client.UnitTests.csproj b/SafeExamBrowser.Client.UnitTests/SafeExamBrowser.Client.UnitTests.csproj
index 71509fed..11f0ebb9 100644
--- a/SafeExamBrowser.Client.UnitTests/SafeExamBrowser.Client.UnitTests.csproj
+++ b/SafeExamBrowser.Client.UnitTests/SafeExamBrowser.Client.UnitTests.csproj
@@ -71,6 +71,14 @@
     </Reference>
     <Reference Include="System" />
     <Reference Include="System.Configuration" />
+    <Reference Include="System.IO.FileSystem.Primitives, Version=4.0.2.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
+      <HintPath>..\packages\System.IO.FileSystem.Primitives.4.3.0\lib\net46\System.IO.FileSystem.Primitives.dll</HintPath>
+      <Private>True</Private>
+      <Private>True</Private>
+    </Reference>
+    <Reference Include="System.IO.Packaging, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
+      <HintPath>..\packages\System.IO.Packaging.5.0.0\lib\net46\System.IO.Packaging.dll</HintPath>
+    </Reference>
     <Reference Include="System.Runtime.CompilerServices.Unsafe, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
       <HintPath>..\packages\System.Runtime.CompilerServices.Unsafe.5.0.0\lib\net45\System.Runtime.CompilerServices.Unsafe.dll</HintPath>
     </Reference>
@@ -80,6 +88,7 @@
     <Reference Include="System.ValueTuple, Version=4.0.3.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
       <HintPath>..\packages\System.ValueTuple.4.5.0\lib\net47\System.ValueTuple.dll</HintPath>
     </Reference>
+    <Reference Include="WindowsBase" />
   </ItemGroup>
   <ItemGroup>
     <Compile Include="Operations\ApplicationOperationTests.cs" />
diff --git a/SafeExamBrowser.Client.UnitTests/packages.config b/SafeExamBrowser.Client.UnitTests/packages.config
index 8a3d95b0..e2097cad 100644
--- a/SafeExamBrowser.Client.UnitTests/packages.config
+++ b/SafeExamBrowser.Client.UnitTests/packages.config
@@ -4,6 +4,8 @@
   <package id="Moq" version="4.16.0" targetFramework="net472" />
   <package id="MSTest.TestAdapter" version="2.1.2" targetFramework="net472" />
   <package id="MSTest.TestFramework" version="2.1.2" targetFramework="net472" />
+  <package id="System.IO.FileSystem.Primitives" version="4.3.0" targetFramework="net472" />
+  <package id="System.IO.Packaging" version="5.0.0" targetFramework="net472" />
   <package id="System.Runtime.CompilerServices.Unsafe" version="5.0.0" targetFramework="net472" />
   <package id="System.Threading.Tasks.Extensions" version="4.5.4" targetFramework="net472" />
   <package id="System.ValueTuple" version="4.5.0" targetFramework="net472" />