diff --git a/lib/preprocessor.js b/lib/preprocessor.js
index 392c5eb48..f61781987 100644
--- a/lib/preprocessor.js
+++ b/lib/preprocessor.js
@@ -89,6 +89,9 @@ var createPreprocessor = function(config, basePath, injector) {
     }
 
     return fs.readFile(file.originalPath, function(err, buffer) {
+      if (err) {
+        throw err;
+      }
       file.sha = sha1(buffer);
       nextPreprocessor(null, thisFileIsBinary ? buffer : buffer.toString());
     });