diff --git a/Assets/UniGLTF/Runtime/Extensions/StringExtensions.cs b/Assets/UniGLTF/Runtime/Extensions/StringExtensions.cs
index 62e3b7170..635e1e0d2 100644
--- a/Assets/UniGLTF/Runtime/Extensions/StringExtensions.cs
+++ b/Assets/UniGLTF/Runtime/Extensions/StringExtensions.cs
@@ -76,6 +76,11 @@ namespace UniGLTF
         // https://docs.unity3d.com/Manual/BestPracticeUnderstandingPerformanceInUnity5.html
         public static bool FastStartsWith(this string a, string b)
         {
+            if (a == null || b == null)
+            {
+                return false;
+            }
+
             var aLen = a.Length;
             var bLen = b.Length;
             if (aLen < bLen)
@@ -94,6 +99,11 @@ namespace UniGLTF
 
         public static bool FastEndsWith(this string a, string b)
         {
+            if (a == null || b == null)
+            {
+                return false;
+            }
+
             var aLen = a.Length;
             var bLen = b.Length;
             if (aLen < bLen)
diff --git a/Assets/UniGLTF/Runtime/UniGLTF/Format/glTFTexture.cs b/Assets/UniGLTF/Runtime/UniGLTF/Format/glTFTexture.cs
index b04b2549c..6ec8065e7 100644
--- a/Assets/UniGLTF/Runtime/UniGLTF/Format/glTFTexture.cs
+++ b/Assets/UniGLTF/Runtime/UniGLTF/Format/glTFTexture.cs
@@ -68,7 +68,7 @@ namespace UniGLTF
                     }
                     else
                     {
-                        return Path.GetExtension(uri).ToLower();
+                        return Path.GetExtension(uri)?.ToLowerInvariant() ?? string.Empty;
                     }
             }
         }