diff --git a/fixtures/f013/A.php b/fixtures/f013/A.php
index aa0393d..ac70988 100644
--- a/fixtures/f013/A.php
+++ b/fixtures/f013/A.php
@@ -2,6 +2,7 @@
 
 namespace DeepCopy\f013;
 
+use BadMethodCallException;
 use Doctrine\Persistence\Proxy;
 
 class A implements Proxy
@@ -11,14 +12,15 @@ class A implements Proxy
     /**
      * @inheritdoc
      */
-    public function __load()
+    public function __load(): void
     {
     }
 
     /**
      * @inheritdoc
      */
-    public function __isInitialized()
+    public function __isInitialized(): bool
     {
+        throw new BadMethodCallException();
     }
 }
diff --git a/fixtures/f013/B.php b/fixtures/f013/B.php
index 89425d8..d1382e6 100644
--- a/fixtures/f013/B.php
+++ b/fixtures/f013/B.php
@@ -2,6 +2,7 @@
 
 namespace DeepCopy\f013;
 
+use BadMethodCallException;
 use Doctrine\Persistence\Proxy;
 
 class B implements Proxy
@@ -11,15 +12,16 @@ class B implements Proxy
     /**
      * @inheritdoc
      */
-    public function __load()
+    public function __load(): void
     {
     }
 
     /**
      * @inheritdoc
      */
-    public function __isInitialized()
+    public function __isInitialized(): bool
     {
+        throw new BadMethodCallException();
     }
 
     public function getFoo()
diff --git a/tests/DeepCopyTest/Matcher/Doctrine/DoctrineProxyMatcherTest.php b/tests/DeepCopyTest/Matcher/Doctrine/DoctrineProxyMatcherTest.php
index 22e380d..38de911 100644
--- a/tests/DeepCopyTest/Matcher/Doctrine/DoctrineProxyMatcherTest.php
+++ b/tests/DeepCopyTest/Matcher/Doctrine/DoctrineProxyMatcherTest.php
@@ -39,7 +39,7 @@ class FooProxy implements Proxy
     /**
      * @inheritdoc
      */
-    public function __load()
+    public function __load(): void
     {
         throw new BadMethodCallException();
     }
@@ -47,7 +47,7 @@ public function __load()
     /**
      * @inheritdoc
      */
-    public function __isInitialized()
+    public function __isInitialized(): bool
     {
         throw new BadMethodCallException();
     }