diff --git a/src/CommonUtilities.FileSystem/src/Commonutilities.FileSystem.csproj b/src/CommonUtilities.FileSystem/src/Commonutilities.FileSystem.csproj
index 1444af2..bd61a57 100644
--- a/src/CommonUtilities.FileSystem/src/Commonutilities.FileSystem.csproj
+++ b/src/CommonUtilities.FileSystem/src/Commonutilities.FileSystem.csproj
@@ -22,6 +22,10 @@
 	</PropertyGroup>
 
 	<ItemGroup>
+		<PackageReference Include="Nullable" Version="1.3.1">
+		  <PrivateAssets>all</PrivateAssets>
+		  <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+		</PackageReference>
 		<PackageReference Include="System.IO.Abstractions" Version="20.0.28" />
 		<PackageReference Include="System.Memory" Version="4.5.5" />
 		<PackageReference Include="TestableIO.System.IO.Abstractions.Analyzers" Version="2022.0.0">
diff --git a/src/CommonUtilities.FileSystem/src/Extensions/PathExtensions.cs b/src/CommonUtilities.FileSystem/src/Extensions/PathExtensions.cs
index 0626dd6..57402e5 100644
--- a/src/CommonUtilities.FileSystem/src/Extensions/PathExtensions.cs
+++ b/src/CommonUtilities.FileSystem/src/Extensions/PathExtensions.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.IO.Abstractions;
 using System.Linq;
@@ -80,7 +81,7 @@ private static bool IsAnyDirectorySeparator(char c)
     /// <param name="driveLetter">If <paramref name="path"/> is drive relative the drive's letter will be stored into this variable.
     /// <see langword="null"/> if <paramref name="path"/> is not drive relative.</param>
     /// <returns>Return <see langword="true"/> if <paramref name="path"/> is relative, but not absolute to a drive; otherwise, <see langword="false"/>.</returns>
-    public static bool IsDriveRelative(this IPath fsPath, string? path, out char? driveLetter)
+    public static bool IsDriveRelative(this IPath fsPath, string? path, [NotNullWhen(true)] out char? driveLetter)
     {
         driveLetter = null;
 
@@ -103,9 +104,9 @@ public static bool IsDriveRelative(this IPath fsPath, string? path, out char? dr
                 driveLetter = path[0];
                 return true;
             }
+
             return false;
         }
-
         return false;
     }