diff --git a/tcpdf.php b/tcpdf.php
index 8238784..d1cf110 100644
--- a/tcpdf.php
+++ b/tcpdf.php
@@ -7796,8 +7796,10 @@ class TCPDF {
 				}
 				closedir($handle);
 			}
-			foreach($this->imagekeys as $file) {
-				unlink($file);
+			if (isset($this->imagekeys)) {
+				foreach($this->imagekeys as $file) {
+					unlink($file);
+				}
 			}
 		}
 		$preserve = array(