diff --git a/rector.php b/rector.php
index b24f7fe82f0..09fb70c3cf8 100644
--- a/rector.php
+++ b/rector.php
@@ -4,6 +4,7 @@
 
 use Rector\CodingStyle\Rector\String_\UseClassKeywordForClassNameResolutionRector;
 use Rector\Config\RectorConfig;
+use Rector\DeadCode\Rector\Cast\RecastingRemovalRector;
 use Rector\DeadCode\Rector\ConstFetch\RemovePhpVersionIdCheckRector;
 use Rector\Php55\Rector\String_\StringClassNameToClassConstantRector;
 
@@ -52,4 +53,9 @@
             __DIR__ . '/src/Configuration/RectorConfigBuilder.php',
             __DIR__ . '/src/Console/Notifier.php',
         ],
+
+        // on php 7.x, substr() result can return false, so force (string) is needed
+        RecastingRemovalRector::class => [
+            __DIR__ . '/rules/CodingStyle/ClassNameImport/ClassNameImportSkipVoter/ClassLikeNameClassNameImportSkipVoter.php',
+        ],
     ]);
diff --git a/rules-tests/DeadCode/Rector/Cast/RecastingRemovalRector/Fixture/skip_substr.php.inc b/rules-tests/DeadCode/Rector/Cast/RecastingRemovalRector/Fixture/skip_substr.php.inc
deleted file mode 100644
index 07f63228bfb..00000000000
--- a/rules-tests/DeadCode/Rector/Cast/RecastingRemovalRector/Fixture/skip_substr.php.inc
+++ /dev/null
@@ -1,17 +0,0 @@
-<?php
-
-namespace Rector\Tests\DeadCode\Rector\Cast\RecastingRemovalRector\Fixture;
-
-/**
- * On PHP 7.4, substr() can returns false
- */
-class SkipSubstr
-{
-    public function run(): string
-    {
-        $className = 'Exception';
-        return (string) substr($className, 0, -strlen($className) - 1);
-    }
-}
-
-?>
diff --git a/rules-tests/DeadCode/Rector/Cast/RecastingRemovalRector/Fixture/with_substr.php.inc b/rules-tests/DeadCode/Rector/Cast/RecastingRemovalRector/Fixture/with_substr.php.inc
new file mode 100644
index 00000000000..4e28363cc08
--- /dev/null
+++ b/rules-tests/DeadCode/Rector/Cast/RecastingRemovalRector/Fixture/with_substr.php.inc
@@ -0,0 +1,29 @@
+<?php
+
+namespace Rector\Tests\DeadCode\Rector\Cast\RecastingRemovalRector\Fixture;
+
+class WithSubstr
+{
+    public function run(): string
+    {
+        $className = 'Exception';
+        return (string) substr($className, 0, -strlen($className) - 1);
+    }
+}
+
+?>
+-----
+<?php
+
+namespace Rector\Tests\DeadCode\Rector\Cast\RecastingRemovalRector\Fixture;
+
+class WithSubstr
+{
+    public function run(): string
+    {
+        $className = 'Exception';
+        return substr($className, 0, -strlen($className) - 1);
+    }
+}
+
+?>
\ No newline at end of file
diff --git a/rules/DeadCode/Rector/Cast/RecastingRemovalRector.php b/rules/DeadCode/Rector/Cast/RecastingRemovalRector.php
index fa2f3ce3fbd..616459d996a 100644
--- a/rules/DeadCode/Rector/Cast/RecastingRemovalRector.php
+++ b/rules/DeadCode/Rector/Cast/RecastingRemovalRector.php
@@ -13,14 +13,12 @@
 use PhpParser\Node\Expr\Cast\Int_;
 use PhpParser\Node\Expr\Cast\Object_;
 use PhpParser\Node\Expr\Cast\String_;
-use PhpParser\Node\Expr\FuncCall;
 use PhpParser\Node\Expr\MethodCall;
 use PhpParser\Node\Expr\StaticCall;
 use PHPStan\Reflection\Php\PhpPropertyReflection;
 use PHPStan\Type\ArrayType;
 use PHPStan\Type\BooleanType;
 use PHPStan\Type\Constant\ConstantArrayType;
-use PHPStan\Type\Constant\ConstantBooleanType;
 use PHPStan\Type\FloatType;
 use PHPStan\Type\IntegerType;
 use PHPStan\Type\MixedType;
@@ -105,13 +103,6 @@ public function refactor(Node $node): ?Node
             return null;
         }
 
-        // substr can return false on php 7.x
-        if ($node->expr instanceof FuncCall
-            && $this->isName($node->expr, 'substr')
-            && ! $node->expr->isFirstClassCallable()) {
-            $nodeType = new UnionType([new StringType(), new ConstantBooleanType(false)]);
-        }
-
         if ($nodeType instanceof ConstantArrayType && $nodeClass === Array_::class) {
             if ($this->shouldSkip($node->expr)) {
                 return null;