diff --git a/src/WireMock.Net/Matchers/GraphQLMatcher.cs b/src/WireMock.Net/Matchers/GraphQLMatcher.cs
index cb66c6288..6bba41635 100644
--- a/src/WireMock.Net/Matchers/GraphQLMatcher.cs
+++ b/src/WireMock.Net/Matchers/GraphQLMatcher.cs
@@ -137,9 +137,14 @@ private static bool TryGetGraphQLRequest(string input, [NotNullWhen(true)] out G
         }
     }
 
-    private static ISchema BuildSchema(string schema)
+    private static ISchema BuildSchema(string typeDefinitions)
     {
-        return Schema.For(schema);
+        var schema = Schema.For(typeDefinitions);
+
+        // #984
+        schema.RegisterTypes(schema.BuiltInTypeMappings.Select(x => x.graphType).ToArray());
+
+        return schema;
     }
 }
 #endif
\ No newline at end of file
diff --git a/test/WireMock.Net.Tests/Matchers/GraphQLMatcherTests.cs b/test/WireMock.Net.Tests/Matchers/GraphQLMatcherTests.cs
index cad8de3f9..3efc32a2a 100644
--- a/test/WireMock.Net.Tests/Matchers/GraphQLMatcherTests.cs
+++ b/test/WireMock.Net.Tests/Matchers/GraphQLMatcherTests.cs
@@ -11,7 +11,10 @@ namespace WireMock.Net.Tests.Matchers;
 public class GraphQLMatcherTests
 {
     private const string TestSchema = @"
+  scalar DateTime
+
   input MessageInput {
+    date: DateTime
     content: String
     author: String
   }
@@ -24,20 +27,21 @@ type Message {
 
   type Mutation {
     createMessage(input: MessageInput): Message
+    createAnotherMessage(date: DateTime, content: String, author: String): Message
     updateMessage(id: ID!, input: MessageInput): Message
   }
 
   type Query {
-   greeting:String
-   students:[Student]
-   studentById(id:ID!):Student
+    greeting: String
+    students: [Student]
+    studentById(id: ID!):Student
   }
 
   type Student {
-   id:ID!
-   firstName:String
-   lastName:String
-   fullName:String 
+    id: ID!
+    firstName: String
+    lastName: String
+    fullName: String 
   }";
 
     [Fact]
@@ -57,7 +61,7 @@ public void GraphQLMatcher_For_ValidSchema_And_CorrectQuery_IsMatch()
     }
 
     [Fact]
-    public void GraphQLMatcher_For_ValidSchema_And_CorrectGraphQLQuery_IsMatch()
+    public void GraphQLMatcher_For_ValidSchema_And_CorrectGraphQL_Query_IsMatch()
     {
         // Arrange
         var input = @"{
@@ -76,6 +80,25 @@ public void GraphQLMatcher_For_ValidSchema_And_CorrectGraphQLQuery_IsMatch()
         matcher.GetPatterns().Should().Contain(TestSchema);
     }
 
+    [Fact]
+    public void GraphQLMatcher_For_ValidSchema_And_CorrectGraphQL_Mutation_IsMatch()
+    {
+        // Arrange
+        var input = @"{
+    ""query"": ""mutation CreateAnotherMessage($date: DateTime!, $content: String!, $author: String!) { createAnotherMessage(date: $date, content: $content, author: $author) { id } }"",
+    ""variables"": { ""date"": ""2007-12-03T10:15:30Z"", ""content"": ""--content--"", ""author"": ""--author--"" }
+}";
+
+        // Act
+        var matcher = new GraphQLMatcher(TestSchema);
+        var result = matcher.IsMatch(input);
+
+        // Assert
+        result.Score.Should().Be(MatchScores.Perfect);
+
+        matcher.GetPatterns().Should().Contain(TestSchema);
+    }
+
     [Fact]
     public void GraphQLMatcher_For_ValidSchema_And_IncorrectQuery_IsMismatch()
     {