diff --git a/lib/utils.js b/lib/utils.js
index fe70a0f..247f85f 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -27,7 +27,7 @@ exports.getImageMimeType = function getImageMimeType (imagePath) {
 }
 
 exports.isRevealTheme = function isRevealTheme (theme) {
-  if (fs.existsSync(path.join(process.cwd(), 'public', 'build', 'reveal.js', 'css', 'theme', theme + '.css'))) {
+  if (fs.existsSync(path.join(__dirname, '..', 'public', 'build', 'reveal.js', 'css', 'theme', theme + '.css'))) {
     return theme
   }
   return undefined