diff --git a/src/GraphQL.Authorization.Tests/AuthorizationValidationRuleTests.cs b/src/GraphQL.Authorization.Tests/AuthorizationValidationRuleTests.cs
index c6854be..c086d33 100644
--- a/src/GraphQL.Authorization.Tests/AuthorizationValidationRuleTests.cs
+++ b/src/GraphQL.Authorization.Tests/AuthorizationValidationRuleTests.cs
@@ -109,6 +109,40 @@ public void nested_type_policy_fail()
             });
         }
 
+        [Fact]
+        public void passes_with_claim_on_input_type()
+        {
+            Settings.AddPolicy("FieldPolicy", _ =>
+            {
+                _.RequireClaim("admin");
+            });
+
+            ShouldPassRule(_=>
+            {
+                _.Query = @"query { author(input: { name: ""Quinn"" }) }";
+                _.Schema = TypedSchema();
+                _.User = CreatePrincipal(claims: new Dictionary<string, string>
+                    {
+                        {"Admin", "true"}
+                    });
+            });
+        }
+
+        [Fact]
+        public void fails_on_missing_claim_on_input_type()
+        {
+            Settings.AddPolicy("FieldPolicy", _ =>
+            {
+                _.RequireClaim("admin");
+            });
+
+            ShouldFailRule(_=>
+            {
+                _.Query = @"query { author(input: { name: ""Quinn"" }) }";
+                _.Schema = TypedSchema();
+            });
+        }
+
         private ISchema BasicSchema()
         {
             var defs = @"
@@ -172,5 +206,24 @@ public class Author
         {
             public string Name { get; set;}
         }
+
+        private ISchema TypedSchema()
+        {
+            var query = new ObjectGraphType();
+            query.Field<StringGraphType>(
+                "author",
+                arguments: new QueryArguments(new QueryArgument<AuthorInputType> { Name = "input" }),
+                resolve: context => "testing"
+            );
+            return new Schema { Query = query };
+        }
+
+        public class AuthorInputType : InputObjectGraphType<Author>
+        {
+            public AuthorInputType()
+            {
+                Field(x => x.Name).AuthorizeWith("FieldPolicy");
+            }
+        }
     }
 }
diff --git a/src/GraphQL.Authorization/AuthorizationValidationRule.cs b/src/GraphQL.Authorization/AuthorizationValidationRule.cs
index 4f0a27b..098ce4c 100644
--- a/src/GraphQL.Authorization/AuthorizationValidationRule.cs
+++ b/src/GraphQL.Authorization/AuthorizationValidationRule.cs
@@ -41,7 +41,7 @@ public INodeVisitor Validate(ValidationContext context)
                     if (argumentType == null)
                         return;
 
-                    var fieldType = argumentType.Fields.First(p => p.Name == objectFieldAst.Name);
+                    var fieldType = argumentType.GetField(objectFieldAst.Name);
                     CheckAuth(objectFieldAst, fieldType, userContext, context, operationType);
                 });