diff --git a/addon/lib/extension.js b/addon/lib/extension.js
index d65716a..458ec8b 100644
--- a/addon/lib/extension.js
+++ b/addon/lib/extension.js
@@ -65,7 +65,7 @@ function isArchive(filename) {
 }
 
 function isExtension(filename, extensions) {
-  const extensionMatch = filename.match(/\.(\w{2,4})$/);
+  const extensionMatch = filename && filename.match(/\.(\w{2,4})$/);
   return extensionMatch && extensions.includes(extensionMatch[1].toLowerCase());
 }