diff --git a/src/Psalm/Internal/Analyzer/ClassLikeAnalyzer.php b/src/Psalm/Internal/Analyzer/ClassLikeAnalyzer.php
index 7f561aa4e..de2867467 100644
--- a/src/Psalm/Internal/Analyzer/ClassLikeAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/ClassLikeAnalyzer.php
@@ -335,7 +335,7 @@ abstract class ClassLikeAnalyzer extends SourceAnalyzer
 
 
         $classUnion = new Union([new TNamedObject($fq_class_name)]);
-        foreach ($class_storage->parent_classes as $parent_class) {
+        foreach ($class_storage->parent_classes + $class_storage->direct_class_interfaces as $parent_class) {
             $parent_storage = $codebase->classlikes->getStorageFor($parent_class);
             if ($parent_storage && $parent_storage->inheritors) {
                 if (!UnionTypeComparator::isContainedBy($codebase, $classUnion, $parent_storage->inheritors)) {
diff --git a/tests/ClassTest.php b/tests/ClassTest.php
index 9504ef226..4a8d7f77d 100644
--- a/tests/ClassTest.php
+++ b/tests/ClassTest.php
@@ -909,6 +909,34 @@ class ClassTest extends TestCase
                     $b = new BarClass();
                     PHP,
             ],
+            'InterfaceInheritorIsAllowed' => [
+                'code' => <<<'PHP'
+                    <?php
+                    /**
+                     * @psalm-inheritors FooClass|BarClass
+                     */
+                    interface BaseInterface {}
+                    class FooClass implements BaseInterface {}
+                    $a = new FooClass();
+                    class BarClass implements BaseInterface {}
+                    $b = new BarClass();
+                    PHP,
+                ],
+                'MultiInterfaceInheritorIsAllowed' => [
+                    'code' => <<<'PHP'
+                    <?php
+                    /**
+                     * @psalm-inheritors FooClass|BarClass
+                     */
+                    interface InterfaceA {}
+                    /**
+                     * @psalm-inheritors FooClass|BarClass
+                     */
+                    interface InterfaceB {}
+                    class FooClass implements InterfaceA, InterfaceB {}
+                    $a = new FooClass();
+                    PHP,
+            ],
         ];
     }
 
@@ -1368,6 +1396,36 @@ class ClassTest extends TestCase
                 'error_message' => 'InvalidExtendClass',
                 'ignored_issues' => [],
             ],
+            'classCannotImplementIfNotInInheritors' => [
+                'code' => <<<'PHP'
+                    <?php
+                    /**
+                     * @psalm-inheritors FooClass|BarClass
+                     */
+                    interface BaseInterface {}
+                    class BazClass implements BaseInterface {}
+                    $a = new BazClass();
+                    PHP,
+                'error_message' => 'InvalidExtendClass',
+                'ignored_issues' => [],
+            ],
+            'UnfulfilledInterfaceInheritors' => [
+                'code' => <<<'PHP'
+                    <?php
+                    /**
+                     * @psalm-inheritors FooClass
+                     */
+                    interface InterfaceA {}
+                    /**
+                     * @psalm-inheritors BarClass
+                     */
+                    interface InterfaceB {}
+                    class BazClass implements InterFaceA, InterFaceB {}
+                    $a = new BazClass();
+                    PHP,
+                'error_message' => 'InvalidExtendClass',
+                'ignored_issues' => [],
+            ],
         ];
     }
 }