diff --git a/src/Translator.php b/src/Translator.php
index 676618a3..ce370f1e 100644
--- a/src/Translator.php
+++ b/src/Translator.php
@@ -3249,8 +3249,8 @@ CODE;
             Type::STR => [['kind' => 'isString']],
             Type::ARRAY => [['kind' => 'isArray']],
             Type::RESOURCE => [['kind' => 'isResource']],
-            Type::OBJECT => $arg->class
-                ? [['kind' => 'instanceof', 'class' => $arg->class]]
+            Type::OBJECT => $arg->declaredClass
+                ? [['kind' => 'instanceof', 'class' => $arg->declaredClass]]
                 : [['kind' => 'isObject']],
             default => null,
         };
diff --git a/tests/compiler/namespace/interface-impl-param-type-cross-ns.phpt b/tests/compiler/namespace/interface-impl-param-type-cross-ns.phpt
new file mode 100644
index 00000000..acaec9e6
--- /dev/null
+++ b/tests/compiler/namespace/interface-impl-param-type-cross-ns.phpt
@@ -0,0 +1,48 @@
+--TEST--
+Cross-namespace interface implementation with an interface-typed parameter must not be reported as incompatible
+--FILE--
+<?php
+namespace A {
+    use B\I1;
+    use B\I2;
+
+    abstract class Test implements I2
+    {
+        public function test(I1 $a): bool
+        {
+            return true;
+        }
+    }
+}
+
+namespace B {
+    interface I1
+    {
+    }
+
+    interface I2
+    {
+        public function test(I1 $a): bool;
+    }
+
+    class Impl1 implements I1
+    {
+    }
+}
+
+namespace {
+    class Concrete extends \A\Test
+    {
+    }
+
+    function main()
+    {
+        $obj = new Concrete();
+        var_dump($obj->test(new \B\Impl1()));
+        echo "done\n";
+    }
+}
+?>
+--EXPECT--
+bool(true)
+done