diff --git a/composer.json b/composer.json
index ae232f5..337b438 100644
--- a/composer.json
+++ b/composer.json
@@ -35,7 +35,7 @@
   },
   "require-dev": {
     "jakub-onderka/php-parallel-lint": "0.8.*",
-    "phpstan/phpstan": "^0.11.5",
+    "phpstan/phpstan": "^1.10.3",
     "squizlabs/php_codesniffer": "^3.4",
     "phperf/xh-tool": "^1.1",
     "phpunit/phpunit": "^4.8"
diff --git a/src/Check/ReturnCheck.php b/src/Check/ReturnCheck.php
index 10b0eea..36d6d81 100644
--- a/src/Check/ReturnCheck.php
+++ b/src/Check/ReturnCheck.php
@@ -32,20 +32,26 @@ public function check(FileInfo $file)
                 continue;
             }
 
-            if ($method['return'] === 'array' && substr($method['docblock']['return'], -2) === '[]') {
+            $returnTypes = $method['docblock']['return'];
+            $methodTypes = $method['return'];
+
+            if ($method['return'] === 'array'
+                && !is_array($returnTypes)
+                && substr($returnTypes, -2) === '[]'
+            ) {
                 // Do nothing because this is fine.
                 continue;
             }
 
-            if ($method['return'] !== $method['docblock']['return']) {
+            if ($methodTypes !== $returnTypes) {
                 $this->fileStatus->add(
                     new ReturnMismatchWarning(
                         $file->getFileName(),
                         $name,
                         $method['line'],
                         $name,
-                        is_array($method['return']) ? implode('|', $method['return']) : $method['return'],
-                        $method['docblock']['return']
+                        is_array($methodTypes) ? implode('|', $methodTypes) : $methodTypes,
+                        is_array($returnTypes) ? implode('|', $returnTypes) : $returnTypes
                     )
                 );
                 continue;
diff --git a/src/FileParser/FileParser.php b/src/FileParser/FileParser.php
index 606ece8..2f4b660 100644
--- a/src/FileParser/FileParser.php
+++ b/src/FileParser/FileParser.php
@@ -14,6 +14,7 @@
 use PhpParser\Node\Stmt\ClassMethod;
 use PhpParser\Node\Stmt\Namespace_;
 use PhpParser\Node\Stmt\Use_;
+use PhpParser\Node\UnionType;
 use PhpParser\NodeAbstract;
 use PhpParser\Parser;
 
@@ -120,6 +121,8 @@ protected function processStatements($file, array $statements, $prefix = '')
 
                     if ($type instanceof NullableType) {
                         $type = $type->type->toString();
+                    } elseif ($type instanceof UnionType) {
+                        $type = trim(implode('|', $type->types));
                     } elseif ($type instanceof NodeAbstract) {
                         $type = $type->toString();
                     }
@@ -154,6 +157,8 @@ protected function processStatements($file, array $statements, $prefix = '')
 
                         if ($type instanceof NullableType) {
                             $type = $type->type->toString();
+                        } elseif ($type instanceof UnionType) {
+                            $type = trim(implode('|', $type->types));
                         } elseif ($type instanceof NodeAbstract) {
                             $type = $type->toString();
                         }