diff --git a/src/GitVersion.Core.Tests/VersionCalculation/Strategies/ConfigNextVersionBaseVersionStrategyTests.cs b/src/GitVersion.Core.Tests/VersionCalculation/Strategies/ConfigNextVersionBaseVersionStrategyTests.cs
index 1f48aa2e24..6db52ed9f4 100644
--- a/src/GitVersion.Core.Tests/VersionCalculation/Strategies/ConfigNextVersionBaseVersionStrategyTests.cs
+++ b/src/GitVersion.Core.Tests/VersionCalculation/Strategies/ConfigNextVersionBaseVersionStrategyTests.cs
@@ -49,6 +49,8 @@ public void ConfigNextVersionTest(string nextVersion, string expectedVersion)
         var branchMock = GitToolsTestingExtensions.CreateMockBranch("main", GitToolsTestingExtensions.CreateMockCommit());
         var branchConfiguration = context.Configuration.GetBranchConfiguration(branchMock);
         var effectiveConfiguration = new EffectiveConfiguration(context.Configuration, branchConfiguration);
+
+        strategy.ShouldNotBeNull();
         return strategy.GetBaseVersions(new(branchMock, effectiveConfiguration)).SingleOrDefault();
     }
 }
diff --git a/src/GitVersion.Core.Tests/VersionCalculation/Strategies/MergeMessageBaseVersionStrategyTests.cs b/src/GitVersion.Core.Tests/VersionCalculation/Strategies/MergeMessageBaseVersionStrategyTests.cs
index 396755a2eb..c3673bf7a4 100644
--- a/src/GitVersion.Core.Tests/VersionCalculation/Strategies/MergeMessageBaseVersionStrategyTests.cs
+++ b/src/GitVersion.Core.Tests/VersionCalculation/Strategies/MergeMessageBaseVersionStrategyTests.cs
@@ -40,6 +40,8 @@ public void ShouldNotAllowIncrementOfVersion()
         var context = contextBuilder.ServicesProvider.GetRequiredService<Lazy<GitVersionContext>>().Value;
         var branchConfiguration = context.Configuration.GetBranchConfiguration(mockBranch);
         var effectiveConfiguration = new EffectiveConfiguration(context.Configuration, branchConfiguration);
+
+        strategy.ShouldNotBeNull();
         var baseVersion = strategy.GetBaseVersions(new(mockBranch, effectiveConfiguration)).Single();
 
         baseVersion.ShouldIncrement.ShouldBe(false);
@@ -173,6 +175,8 @@ private static void AssertMergeMessage(string message, string? expectedVersion,
         var context = contextBuilder.ServicesProvider.GetRequiredService<Lazy<GitVersionContext>>().Value;
         var branchConfiguration = context.Configuration.GetBranchConfiguration(mockBranch);
         var effectiveConfiguration = new EffectiveConfiguration(context.Configuration, branchConfiguration);
+
+        strategy.ShouldNotBeNull();
         var baseVersion = strategy.GetBaseVersions(new(mockBranch, effectiveConfiguration)).SingleOrDefault();
 
         if (expectedVersion == null)
diff --git a/src/GitVersion.Core.Tests/VersionCalculation/Strategies/VersionInBranchNameBaseVersionStrategyTests.cs b/src/GitVersion.Core.Tests/VersionCalculation/Strategies/VersionInBranchNameBaseVersionStrategyTests.cs
index da49ec0d21..2ffd0b1cc3 100644
--- a/src/GitVersion.Core.Tests/VersionCalculation/Strategies/VersionInBranchNameBaseVersionStrategyTests.cs
+++ b/src/GitVersion.Core.Tests/VersionCalculation/Strategies/VersionInBranchNameBaseVersionStrategyTests.cs
@@ -25,6 +25,8 @@ public void CanTakeVersionFromNameOfReleaseBranch(string branchName, string expe
         var configuration = GitFlowConfigurationBuilder.New.Build();
         var branchConfiguration = configuration.GetBranchConfiguration(branchName);
         var effectiveConfiguration = new EffectiveConfiguration(configuration, branchConfiguration);
+
+        strategy.ShouldNotBeNull();
         var baseVersion = strategy.GetBaseVersions(new(gitRepository.FindBranch(branchName)!, effectiveConfiguration)).Single();
 
         baseVersion.SemanticVersion.ToString().ShouldBe(expectedBaseVersion);
@@ -45,6 +47,8 @@ public void ShouldNotTakeVersionFromNameOfNonReleaseBranch(string branchName)
         var configuration = GitFlowConfigurationBuilder.New.Build();
         var branchConfiguration = configuration.GetBranchConfiguration(branchName);
         var effectiveConfiguration = new EffectiveConfiguration(configuration, branchConfiguration);
+
+        strategy.ShouldNotBeNull();
         var baseVersions = strategy.GetBaseVersions(new(gitRepository.FindBranch(branchName)!, effectiveConfiguration));
 
         baseVersions.ShouldBeEmpty();
@@ -67,6 +71,9 @@ public void CanTakeVersionFromNameOfConfiguredReleaseBranch(string branchName, s
         var configuration = GitFlowConfigurationBuilder.New.Build();
         var branchConfiguration = configuration.GetBranchConfiguration(branchName);
         var effectiveConfiguration = new EffectiveConfiguration(configuration, branchConfiguration);
+
+        strategy.ShouldNotBeNull();
+
         var baseVersion = strategy.GetBaseVersions(new(gitRepository.FindBranch(branchName)!, effectiveConfiguration)).Single();
 
         baseVersion.SemanticVersion.ToString().ShouldBe(expectedBaseVersion);
@@ -90,12 +97,15 @@ public void CanTakeVersionFromNameOfRemoteReleaseBranch(string branchName, strin
         var configuration = GitFlowConfigurationBuilder.New.Build();
         var branchConfiguration = configuration.GetBranchConfiguration(branchName);
         var effectiveConfiguration = new EffectiveConfiguration(configuration, branchConfiguration);
+
+        strategy.ShouldNotBeNull();
+
         var baseVersion = strategy.GetBaseVersions(new(gitRepository.FindBranch(branchName)!, effectiveConfiguration)).Single();
 
         baseVersion.SemanticVersion.ToString().ShouldBe(expectedBaseVersion);
     }
 
-    private static IVersionStrategy GetVersionStrategy(string workingDirectory, IGitRepository repository, string branch, GitVersionConfiguration? configuration = null)
+    private static IVersionStrategy? GetVersionStrategy(string workingDirectory, IGitRepository repository, string branch, GitVersionConfiguration? configuration = null)
     {
         var sp = BuildServiceProvider(workingDirectory, repository, branch, configuration);
         return sp.GetServiceForType<IVersionStrategy, VersionInBranchNameVersionStrategy>();
diff --git a/src/GitVersion.Core/Extensions/ServiceCollectionExtensions.cs b/src/GitVersion.Core/Extensions/ServiceCollectionExtensions.cs
index d4d6467f3d..3ab937a31f 100644
--- a/src/GitVersion.Core/Extensions/ServiceCollectionExtensions.cs
+++ b/src/GitVersion.Core/Extensions/ServiceCollectionExtensions.cs
@@ -10,6 +10,6 @@ public static IServiceCollection AddModule(this IServiceCollection serviceCollec
         return serviceCollection;
     }
 
-    public static TService GetServiceForType<TService, TType>(this IServiceProvider serviceProvider) =>
+    public static TService? GetServiceForType<TService, TType>(this IServiceProvider serviceProvider) =>
         serviceProvider.GetServices<TService>().SingleOrDefault(t => t?.GetType() == typeof(TType));
 }