diff --git a/src/Psalm/Internal/Analyzer/ClassAnalyzer.php b/src/Psalm/Internal/Analyzer/ClassAnalyzer.php
index e920468f1..0f1d9978f 100644
--- a/src/Psalm/Internal/Analyzer/ClassAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/ClassAnalyzer.php
@@ -232,6 +232,10 @@ class ClassAnalyzer extends ClassLikeAnalyzer
             }
         }
 
+        if ($storage->invalid_dependencies) {
+            return;
+        }
+
         $class_interfaces = $storage->class_implements;
 
         if (!$class->isAbstract()) {
diff --git a/tests/ClassTest.php b/tests/ClassTest.php
index 34d500005..8e85290c2 100644
--- a/tests/ClassTest.php
+++ b/tests/ClassTest.php
@@ -308,6 +308,18 @@ class ClassTest extends TestCase
                         }
                     }',
             ],
+            'noCrashWhenIgnoringUndefinedClass' => [
+                '<?php
+                    class A extends B {
+                        public function foo() {
+                            parent::bar();
+                        }
+                    }',
+                'assertions' => [],
+                'error_levels' => [
+                    'UndefinedClass'
+                ],
+            ],
         ];
     }