diff --git a/lib/pbxProject.js b/lib/pbxProject.js
index 4056e40..532a27e 100644
--- a/lib/pbxProject.js
+++ b/lib/pbxProject.js
@@ -973,10 +973,13 @@
     if (file.fileEncoding)
         obj.fileEncoding = file.fileEncoding;
 
+    if (file.lastKnownFileType)
+        obj.lastKnownFileType = file.lastKnownFileType;
+
     if (file.explicitFileType)
         obj.explicitFileType = file.explicitFileType;
 
-    if ('includeInIndex' in file)
+    if (file.includeInIndex)
         obj.includeInIndex = file.includeInIndex;
 
     return obj;