diff --git a/lib/file-list.js b/lib/file-list.js
index b3b27b866..13129cd32 100644
--- a/lib/file-list.js
+++ b/lib/file-list.js
@@ -176,7 +176,7 @@ class FileList {
         const file = new File(path, mtime, doNotCache, type)
 
         if (file.doNotCache) {
-          log.debug('Not preprocessing "%s" due to nocache')
+          log.debug('Not preprocessing "%s" due to nocache', pattern)
           return Promise.resolve(file)
         }