diff --git a/src/Support/RuleFactory.php b/src/Support/RuleFactory.php
index bd48324..05e4557 100644
--- a/src/Support/RuleFactory.php
+++ b/src/Support/RuleFactory.php
@@ -5,9 +5,9 @@ declare(strict_types=1);
 namespace Icefox\DTO\Support;
 
 use Icefox\DTO\Attributes\CastWith;
+use Icefox\DTO\Attributes\Flat;
 use Icefox\DTO\Attributes\OverwriteRules;
 use Icefox\DTO\Config;
-use Icefox\DTO\Attributes\FromMapper;
 use Icefox\DTO\Log;
 use Icefox\DTO\ParameterMeta;
 use Icefox\DTO\ReflectionHelper;
@@ -15,16 +15,12 @@ use Illuminate\Support\Facades\App;
 use Illuminate\Validation\Rule;
 use ReflectionClass;
 use ReflectionNamedType;
-use ReflectionParameter;
 use ReflectionUnionType;
 use BackedEnum;
-use phpDocumentor\Reflection\DocBlockFactory;
-use phpDocumentor\Reflection\DocBlock\Tag;
 use phpDocumentor\Reflection\DocBlock\Tags\Param;
 use phpDocumentor\Reflection\Type;
 use phpDocumentor\Reflection\Types\AbstractList;
 use phpDocumentor\Reflection\Types\Boolean;
-use phpDocumentor\Reflection\Types\ContextFactory;
 use phpDocumentor\Reflection\Types\Float_;
 use phpDocumentor\Reflection\Types\Integer;
 use phpDocumentor\Reflection\Types\Nullable;
@@ -61,7 +57,7 @@ class RuleFactory
             $paramsSub = ReflectionHelper::getParametersMeta($type->getFqsen()->__toString());
             $rules = array_merge(
                 $rules,
-                self::infer($paramsSub, $prefix . '.'),
+                self::infer($paramsSub, $prefix),
             );
         }
         return $rules;
@@ -71,10 +67,13 @@ class RuleFactory
      * @param array<ParameterMeta> $parameters
      * @return array<string,array<int,string|Rule>>
      */
-    public static function infer(array $parameters, string $prefix): array
+    public static function infer(array $parameters, string $basePrefix): array
     {
         $rules = [];
         foreach ($parameters as $parameter) {
+            $prefix = $basePrefix
+                . (empty($basePrefix) ? '' : '.')
+                . (empty($parameter->reflection->getAttributes(Flat::class)) ? $parameter->reflection->getName() : '');
             foreach (self::buildParameterRule($parameter, $prefix) as $key => $newRules) {
                 $rules[$key] = $newRules;
             }
@@ -89,18 +88,17 @@ class RuleFactory
     {
         $type = $parameter->reflection->getType();
 
-        $root = $prefix . $parameter->reflection->getName();
         if (empty($type)) {
-            return [$root => $parameter->reflection->isOptional() ? ['sometimes'] : ['required']];
+            return [$prefix => $parameter->reflection->isOptional() ? ['sometimes'] : ['required']];
         }
 
-        $rules = [$root => []];
+        $rules = [$prefix => []];
         if ($parameter->reflection->isOptional()) {
-            $rules[$root][] = 'sometimes';
+            $rules[$prefix][] = 'sometimes';
         } elseif ($type->allowsNull()) {
-            $rules[$root][] = 'nullable';
+            $rules[$prefix][] = 'nullable';
         } else {
-            $rules[$root][] = 'required';
+            $rules[$prefix][] = 'required';
         }
 
         if ($type instanceof ReflectionUnionType) {
@@ -111,27 +109,27 @@ class RuleFactory
         if ($type instanceof ReflectionNamedType && $name = $type->getName()) {
             if ($globalRules = Config::getRules($name)) {
                 foreach ($globalRules($parameter->reflection, $parameter->tag->getType()) as $scopedPrefix => $values) {
-                    $realPrefix = $root . $scopedPrefix;
+                    $realPrefix = $prefix . $scopedPrefix;
                     $rules[$realPrefix] = array_values(array_unique(array_merge($rules[$realPrefix] ?? [], $values)));
                 }
             }
             if ($name === 'string') {
             } elseif ($name === 'bool') {
-                $rules[$root][] = 'boolean';
+                $rules[$prefix][] = 'boolean';
             } elseif ($name === 'int' || $name === 'float') {
-                $rules[$root][] = 'numeric';
+                $rules[$prefix][] = 'numeric';
             } elseif ($name === 'array') {
-                $rules[$root][] = 'array';
+                $rules[$prefix][] = 'array';
             } elseif (enum_exists($name)) {
                 $ref = new ReflectionClass($name);
                 if ($ref->isSubclassOf(BackedEnum::class)) {
-                    $rules[$root][] = Rule::enum($name);
+                    $rules[$prefix][] = Rule::enum($name);
                 }
             } else {
                 $paramsSub = ReflectionHelper::getParametersMeta($type->getName());
                 $rules = array_merge(
                     $rules,
-                    self::infer($paramsSub, $root . '.'),
+                    self::infer($paramsSub, $prefix),
                 );
             }
         }
@@ -141,15 +139,16 @@ class RuleFactory
             if (method_exists($mapperClass, 'rules')) {
                 $subRules = App::call("$mapperClass@rules");
                 foreach ($subRules as $key => &$value) {
-                    $path = empty($key) ? $root : ($root . '.' . $key);
+                    $path = empty($key) ? $prefix : ($prefix . '.' . $key);
                     $rules[$path] = array_values(array_unique(array_merge($rules[$path] ?? [], $value)));
                 }
             }
         }
+
         if ($parameter->tag instanceof Param) {
             $docblockRules = self::getRulesFromDocBlock(
                 $parameter->tag->getType(),
-                $prefix . $parameter->reflection->getName(),
+                $prefix,
             );
             foreach ($docblockRules as $key => &$values) {
                 $rules[$key] = array_values(array_unique(array_merge($rules[$key] ?? [], $values)));
diff --git a/tests/Flattening/Classes/BasicRoot.php b/tests/Flattening/Classes/BasicRoot.php
new file mode 100644
index 0000000..299f858
--- /dev/null
+++ b/tests/Flattening/Classes/BasicRoot.php
@@ -0,0 +1,12 @@
+<?php
+
+namespace Tests\Flattening\Classes;
+
+use Icefox\DTO\Attributes\Flat;
+use Icefox\DTO\DataObject;
+
+class BasicRoot
+{
+    use DataObject;
+    public function __construct(public string $text, #[Flat] public RequiredLeaf $leaf) {}
+}
diff --git a/tests/Flattening/Classes/RequiredLeaf.php b/tests/Flattening/Classes/RequiredLeaf.php
new file mode 100644
index 0000000..4210100
--- /dev/null
+++ b/tests/Flattening/Classes/RequiredLeaf.php
@@ -0,0 +1,12 @@
+<?php
+
+namespace Tests\Flattening\Classes;
+
+use Icefox\DTO\DataObject;
+
+class RequiredLeaf
+{
+    use DataObject;
+
+    public function __construct(public int $value) {}
+}
diff --git a/tests/Flattening/FlatteningTest.php b/tests/Flattening/FlatteningTest.php
new file mode 100644
index 0000000..0ff5547
--- /dev/null
+++ b/tests/Flattening/FlatteningTest.php
@@ -0,0 +1,18 @@
+<?php
+
+namespace Tests\Flattening;
+
+use Icefox\DTO\Log;
+use Icefox\DTO\Support\RuleFactory;
+use Tests\Flattening\Classes\BasicRoot;
+
+describe('flattens required parameters', function () {
+    it('generates correct rules', function () {
+
+        $rules = (new RuleFactory(new Log()))->make(BasicRoot::class);
+        expect($rules)->toMatchArray([
+            'text' => ['required'],
+            'value' => ['required', 'numeric'],
+        ]);
+    });
+});
diff --git a/tests/Rules/RulesTest.php b/tests/Rules/RulesTest.php
index c769acd..fca9610 100644
--- a/tests/Rules/RulesTest.php
+++ b/tests/Rules/RulesTest.php
@@ -15,7 +15,7 @@ use Tests\Rules\WithOverwriteRules;
 describe('rules array shape', function () {
     it('returns inferred rules shape from RuleFactory::infer (inferred only)', function () {
         $parameters = ReflectionHelper::getParametersMeta(WithMergedRules::class);
-        $rules = RuleFactory::infer($parameters, '');
+        $rules = RuleFactory::infer($parameters, '', '');
 
         expect($rules)->toBe([
             'value' => ['required', 'numeric'],
@@ -24,7 +24,7 @@ describe('rules array shape', function () {
 
     it('returns inferred rules shape regardless of OverwriteRules attribute', function () {
         $parameters = ReflectionHelper::getParametersMeta(WithOverwriteRules::class);
-        $rules = RuleFactory::infer($parameters, '');
+        $rules = RuleFactory::infer($parameters, '', '');
 
         expect($rules)->toBe([
             'value' => ['required', 'numeric'],