diff --git a/benchmarks/ScalarOverrideBench.php b/benchmarks/ScalarOverrideBench.php
index e6e6c0b03..34758985c 100644
--- a/benchmarks/ScalarOverrideBench.php
+++ b/benchmarks/ScalarOverrideBench.php
@@ -60,6 +60,7 @@ public function setUp(): void
         $this->schemaTypeLoader = new Schema([
             'query' => $queryTypeLoader,
             'typeLoader' => static fn (string $name): ?Type => $typesForLoader[$name] ?? null,
+            'typeLoaderSupportsScalars' => true,
         ]);
 
         $queryTypeTypes = new ObjectType([
diff --git a/docs/class-reference.md b/docs/class-reference.md
index 21b10dc2c..81b7cd30c 100644
--- a/docs/class-reference.md
+++ b/docs/class-reference.md
@@ -807,6 +807,7 @@ Usage example:
   types?: Types|null,
   directives?: array<Directive>|null,
   typeLoader?: TypeLoader|null,
+  typeLoaderSupportsScalars?: bool|null,
   assumeValid?: bool|null,
   astNode?: SchemaDefinitionNode|null,
   extensionASTNodes?: array<SchemaExtensionNode>|null,
diff --git a/examples/06-per-schema-scalar-override/example.php b/examples/06-per-schema-scalar-override/example.php
index 9aa5bd87b..9f5f81078 100644
--- a/examples/06-per-schema-scalar-override/example.php
+++ b/examples/06-per-schema-scalar-override/example.php
@@ -56,6 +56,7 @@
 $schemaViaTypeLoader = new Schema([
     'query' => $queryTypeForLoader,
     'typeLoader' => static fn (string $name): ?Type => $types[$name] ?? null,
+    'typeLoaderSupportsScalars' => true,
 ]);
 
 $result = GraphQL::executeQuery($schemaViaTypeLoader, '{ greeting(name: "World") }');
diff --git a/src/Type/Schema.php b/src/Type/Schema.php
index 8708552b4..ae3448311 100644
--- a/src/Type/Schema.php
+++ b/src/Type/Schema.php
@@ -188,13 +188,14 @@ public function getTypeMap(): array
                 $allReferencedTypes[$name] = $override;
             }
 
-            if (isset($this->config->typeLoader)) {
+            $typeLoader = $this->config->getTypeLoader();
+            if ($typeLoader && $this->config->getTypeLoaderSupportsScalars()) {
                 foreach (Type::BUILT_IN_SCALAR_NAMES as $scalarName) {
                     if (isset($scalarOverrides[$scalarName])) {
                         continue;
                     }
 
-                    $type = ($this->config->typeLoader)($scalarName);
+                    $type = $typeLoader($scalarName);
                     if ($type instanceof ScalarType
                         && $type->name === $scalarName
                         && $type !== $builtInScalars[$scalarName]
@@ -362,11 +363,16 @@ public function hasType(string $name): bool
      */
     private function loadType(string $typeName): ?Type
     {
-        if (! isset($this->config->typeLoader)) {
+        $typeLoader = $this->config->getTypeLoader();
+        if (! $typeLoader) {
             return $this->getTypeMap()[$typeName] ?? null;
         }
 
-        $type = ($this->config->typeLoader)($typeName);
+        if (! $this->config->getTypeLoaderSupportsScalars() && in_array($typeName, Type::BUILT_IN_SCALAR_NAMES)) {
+            return null;
+        }
+
+        $type = $typeLoader($typeName);
         if ($type === null) {
             return null;
         }
diff --git a/src/Type/SchemaConfig.php b/src/Type/SchemaConfig.php
index abf82dd4f..c1d830bdf 100644
--- a/src/Type/SchemaConfig.php
+++ b/src/Type/SchemaConfig.php
@@ -37,6 +37,7 @@
  *   types?: Types|null,
  *   directives?: array<Directive>|null,
  *   typeLoader?: TypeLoader|null,
+ *   typeLoaderSupportsScalars?: bool|null,
  *   assumeValid?: bool|null,
  *   astNode?: SchemaDefinitionNode|null,
  *   extensionASTNodes?: array<SchemaExtensionNode>|null,
@@ -72,6 +73,8 @@ class SchemaConfig
      */
     public $typeLoader;
 
+    public bool $typeLoaderSupportsScalars = false;
+
     public bool $assumeValid = false;
 
     public ?SchemaDefinitionNode $astNode = null;
@@ -121,6 +124,10 @@ public static function create(array $options = []): self
                 $config->setTypeLoader($options['typeLoader']);
             }
 
+            if (isset($options['typeLoaderSupportsScalars'])) {
+                $config->setTypeLoaderSupportsScalars($options['typeLoaderSupportsScalars']);
+            }
+
             if (isset($options['assumeValid'])) {
                 $config->setAssumeValid($options['assumeValid']);
             }
@@ -298,6 +305,20 @@ public function setTypeLoader(?callable $typeLoader): self
         return $this;
     }
 
+    /** @api */
+    public function getTypeLoaderSupportsScalars(): bool
+    {
+        return $this->typeLoaderSupportsScalars;
+    }
+
+    /** @api */
+    public function setTypeLoaderSupportsScalars(bool $supportsScalars): self
+    {
+        $this->typeLoaderSupportsScalars = $supportsScalars;
+
+        return $this;
+    }
+
     public function getAssumeValid(): bool
     {
         return $this->assumeValid;
diff --git a/tests/Type/ScalarOverridesTest.php b/tests/Type/ScalarOverridesTest.php
index ebee4ca88..d025ca2cb 100644
--- a/tests/Type/ScalarOverridesTest.php
+++ b/tests/Type/ScalarOverridesTest.php
@@ -43,6 +43,7 @@ public function testTypeLoaderOverrideWorksEndToEnd(): void
         $schema = new Schema([
             'query' => $queryType,
             'typeLoader' => static fn (string $name): ?Type => $types[$name] ?? null,
+            'typeLoaderSupportsScalars' => true,
         ]);
 
         $schema->assertValid();
@@ -65,6 +66,7 @@ public function testTypeLoaderOverrideWorksInProductionMode(): void
             $schema = new Schema([
                 'query' => $queryType,
                 'typeLoader' => static fn (string $name): ?Type => $types[$name] ?? null,
+                'typeLoaderSupportsScalars' => true,
             ]);
 
             $result = GraphQL::executeQuery($schema, '{ greeting }');
@@ -117,6 +119,7 @@ public function testIntrospectionUsesOverriddenScalar(): void
         $schema = new Schema([
             'query' => $queryType,
             'typeLoader' => static fn (string $name): ?Type => $types[$name] ?? null,
+            'typeLoaderSupportsScalars' => true,
         ]);
 
         $result = GraphQL::executeQuery($schema, '{ __type(name: "Query") { fields { name } } }');
@@ -128,6 +131,28 @@ public function testIntrospectionUsesOverriddenScalar(): void
         self::assertContains('GREETING', $fieldNames);
     }
 
+    public function testTypeLoaderNotInvokedForScalarsWhenOptInNotSet(): void
+    {
+        $invocations = [];
+        $uppercaseString = self::createUppercaseString();
+        $queryType = self::createQueryType();
+        $types = ['Query' => $queryType, 'String' => $uppercaseString];
+
+        $schema = new Schema([
+            'query' => $queryType,
+            'typeLoader' => static function (string $name) use ($types, &$invocations): ?Type {
+                $invocations[] = $name;
+
+                return $types[$name] ?? null;
+            },
+        ]);
+
+        $result = GraphQL::executeQuery($schema, '{ greeting }');
+
+        self::assertSame(['data' => ['greeting' => 'hello world']], $result->toArray());
+        self::assertNotContains('String', $invocations);
+    }
+
     public function testTwoSchemasWithDifferentOverridesAreIndependent(): void
     {
         $uppercaseString = new CustomScalarType([
@@ -151,6 +176,7 @@ public function testTwoSchemasWithDifferentOverridesAreIndependent(): void
         $schemaB = new Schema([
             'query' => $queryTypeB,
             'typeLoader' => static fn (string $name): ?Type => $typesB[$name] ?? null,
+            'typeLoaderSupportsScalars' => true,
         ]);
 
         $resultA = GraphQL::executeQuery($schemaA, '{ greeting }');
@@ -194,6 +220,7 @@ public function testNonOverriddenScalarsAreUnaffected(): void
         $schema = new Schema([
             'query' => $queryType,
             'typeLoader' => static fn (string $name): ?Type => $types[$name] ?? null,
+            'typeLoaderSupportsScalars' => true,
         ]);
 
         $result = GraphQL::executeQuery($schema, '{ greeting count ratio active identifier }');