diff --git a/src/OSharp.Utils/Reflection/AssemblyExtensions.cs b/src/OSharp.Utils/Reflection/AssemblyExtensions.cs
index bd890021..e23eef2b 100644
--- a/src/OSharp.Utils/Reflection/AssemblyExtensions.cs
+++ b/src/OSharp.Utils/Reflection/AssemblyExtensions.cs
@@ -28,7 +28,7 @@ public static class AssemblyExtensions
         /// </summary>
         public static string GetFileVersion(this Assembly assembly)
         {
-            assembly.CheckNotNull("assembly");
+            assembly.CheckNotNull(nameof(assembly));
             FileVersionInfo info = FileVersionInfo.GetVersionInfo(assembly.Location);
             return info.FileVersion;
         }
@@ -38,10 +38,10 @@ public static string GetFileVersion(this Assembly assembly)
         /// </summary>
         public static string GetProductVersion(this Assembly assembly)
         {
-            assembly.CheckNotNull("assembly");
+            assembly.CheckNotNull(nameof(assembly));
             FileVersionInfo info = FileVersionInfo.GetVersionInfo(assembly.Location);
             string version = info.ProductVersion;
-            if (version.Contains("+"))
+            if (version?.Contains("+") == true)
             {
                 version = version.ReplaceRegex(@"\+(\w+)?", "");
             }
@@ -64,7 +64,7 @@ public static string GetCliVersion()
             CompilationLibrary lib = null;
             foreach (string dllName in dllNames)
             {
-                lib = DependencyContext.Default.CompileLibraries.FirstOrDefault(m => m.Name == dllName);
+                lib = DependencyContext.Default?.CompileLibraries.FirstOrDefault(m => m.Name == dllName);
                 if (lib != null)
                 {
                     break;
@@ -74,4 +74,4 @@ public static string GetCliVersion()
             return cliVersion;
         }
     }
-}
\ No newline at end of file
+}