diff --git a/src/Psalm/Internal/PhpVisitor/Reflector/FunctionLikeNodeScanner.php b/src/Psalm/Internal/PhpVisitor/Reflector/FunctionLikeNodeScanner.php
index f04a90072d0..f0a8f34cc63 100644
--- a/src/Psalm/Internal/PhpVisitor/Reflector/FunctionLikeNodeScanner.php
+++ b/src/Psalm/Internal/PhpVisitor/Reflector/FunctionLikeNodeScanner.php
@@ -825,7 +825,9 @@ private function getTranslatedFunctionParam(
                 $this->codebase->analysis_php_version_id,
             );
 
-            if ($is_nullable) {
+            if ($param_type->isMixed()) {
+                $is_nullable = false;
+            } elseif ($is_nullable) {
                 $param_type = $param_type->getBuilder()->addType(new TNull)->freeze();
             } else {
                 $is_nullable = $param_type->isNullable();
diff --git a/tests/ArgTest.php b/tests/ArgTest.php
index 5fefdbef086..36efb359362 100644
--- a/tests/ArgTest.php
+++ b/tests/ArgTest.php
@@ -355,6 +355,20 @@ function foo($a, ...$b) {}
 
                     var_caller("foo");',
             ],
+            'mixedNullable' => [
+                'code' => '<?php
+                    class A {
+                        public function __construct(public mixed $default = null) {
+                        }
+                    }
+                    $a = new A;
+                    $_v = $a->default;',
+                'assertions' => [
+                    '$_v===' => 'mixed',
+                ],
+                'ignored_issues' => [],
+                'php_version' => '8.0',
+            ],
         ];
     }