diff --git a/SDWebImage/SDWebImageCompat.h b/SDWebImage/SDWebImageCompat.h
index 866d92b2..ec8f088e 100644
--- a/SDWebImage/SDWebImageCompat.h
+++ b/SDWebImage/SDWebImageCompat.h
@@ -93,11 +93,11 @@
     #define SDDispatchQueueSetterSementics assign
 #endif
 
-extern UIImage *SDScaledImageForKey(NSString *key, UIImage *image);
+FOUNDATION_EXPORT UIImage *SDScaledImageForKey(NSString *key, UIImage *image);
 
 typedef void(^SDWebImageNoParamsBlock)();
 
-extern NSString *const SDWebImageErrorDomain;
+FOUNDATION_EXPORT NSString *const SDWebImageErrorDomain;
 
 #ifndef dispatch_main_async_safe
 #define dispatch_main_async_safe(block)\
diff --git a/SDWebImage/SDWebImageDownloader.h b/SDWebImage/SDWebImageDownloader.h
index 7e85bf6b..cdfe7291 100644
--- a/SDWebImage/SDWebImageDownloader.h
+++ b/SDWebImage/SDWebImageDownloader.h
@@ -68,8 +68,8 @@ typedef NS_ENUM(NSInteger, SDWebImageDownloaderExecutionOrder) {
     SDWebImageDownloaderLIFOExecutionOrder
 };
 
-extern NSString * _Nonnull const SDWebImageDownloadStartNotification;
-extern NSString * _Nonnull const SDWebImageDownloadStopNotification;
+FOUNDATION_EXPORT NSString * _Nonnull const SDWebImageDownloadStartNotification;
+FOUNDATION_EXPORT NSString * _Nonnull const SDWebImageDownloadStopNotification;
 
 typedef void(^SDWebImageDownloaderProgressBlock)(NSInteger receivedSize, NSInteger expectedSize, NSURL * _Nullable targetURL);
 
diff --git a/SDWebImage/SDWebImageDownloaderOperation.h b/SDWebImage/SDWebImageDownloaderOperation.h
index b1908550..40721b24 100644
--- a/SDWebImage/SDWebImageDownloaderOperation.h
+++ b/SDWebImage/SDWebImageDownloaderOperation.h
@@ -10,10 +10,10 @@
 #import "SDWebImageDownloader.h"
 #import "SDWebImageOperation.h"
 
-extern NSString * _Nonnull const SDWebImageDownloadStartNotification;
-extern NSString * _Nonnull const SDWebImageDownloadReceiveResponseNotification;
-extern NSString * _Nonnull const SDWebImageDownloadStopNotification;
-extern NSString * _Nonnull const SDWebImageDownloadFinishNotification;
+FOUNDATION_EXPORT NSString * _Nonnull const SDWebImageDownloadStartNotification;
+FOUNDATION_EXPORT NSString * _Nonnull const SDWebImageDownloadReceiveResponseNotification;
+FOUNDATION_EXPORT NSString * _Nonnull const SDWebImageDownloadStopNotification;
+FOUNDATION_EXPORT NSString * _Nonnull const SDWebImageDownloadFinishNotification;