diff --git a/tests/Sniffs/ReturnTypeDeclarationSniffTest.php b/tests/Sniffs/ReturnTypeDeclarationSniffTest.php
index ad687918..a1b59b57 100644
--- a/tests/Sniffs/ReturnTypeDeclarationSniffTest.php
+++ b/tests/Sniffs/ReturnTypeDeclarationSniffTest.php
@@ -71,6 +71,7 @@ public function testNullableReturnTypeHint()
         $analysers  = ['compatibility'];
         $metrics    = self::$api->run($dataSource, $analysers);
         $versions   = $metrics[self::$analyserId]['versions'];
+        $functions  = $metrics[self::$analyserId]['functions'];
 
         $this->assertEquals(
             [
@@ -80,5 +81,15 @@ public function testNullableReturnTypeHint()
             ],
             $versions
         );
+
+        $this->assertEquals(
+            '7.1.0',
+            $functions['testReturn1']['php.min']
+        );
+
+        $this->assertEquals(
+            '7.1.0',
+            $functions['testReturn2']['php.min']
+        );
     }
 }