diff --git a/extensions/curl/AMBuilder b/extensions/curl/AMBuilder
index b5e6377b0..c69974306 100644
--- a/extensions/curl/AMBuilder
+++ b/extensions/curl/AMBuilder
@@ -20,6 +20,8 @@ elif builder.target_platform == 'windows':
 
 binary.sources += [
   'extension.cpp',
+  'FileDownloader.cpp',
+  'MemoryDownloader.cpp',
   'curlapi.cpp',
   '../../public/smsdk_ext.cpp'
 ]