diff --git a/src/ControlStructure/BlockToken.php b/src/ControlStructure/BlockToken.php
index cfa04e6..cd718c1 100644
--- a/src/ControlStructure/BlockToken.php
+++ b/src/ControlStructure/BlockToken.php
@@ -229,10 +229,9 @@ class BlockToken implements ControlStructure {
                 $this->rendering = true;
 
                 if ($this->using['this'] ?? false) {
-                    $thisProxy = $this->using['this'];
-                    unset($this->using['this']);
+                    throw new \InvalidArgumentException("Block '{$this->viewPath}' cannot overwrite 'this' variable.");
                 }
-                
+
                 return $classTemplate->picea->inlineBlock($thisProxy ?? $this, $this->viewPath, ...$this->arguments);
             }