diff --git a/src/PHPePub/Core/EPub.php b/src/PHPePub/Core/EPub.php
index e40b82b..9ee91d5 100644
--- a/src/PHPePub/Core/EPub.php
+++ b/src/PHPePub/Core/EPub.php
@@ -1260,6 +1260,9 @@ function setCoverImage($fileName, $imageData = null, $mimetype = null) {
                 }
             }
             $image = ImageHelper::getImage($this, $fileName);
+            if (false === $image) {
+                return false;
+            }
             $imageData = $image['image'];
             $mimetype = $image['mime'];
             $fileName = preg_replace('#\.[^\.]+$#', "." . $image['ext'], $fileName);