diff --git a/UIKit+AFNetworking/AFAutoPurgingImageCache.m b/UIKit+AFNetworking/AFAutoPurgingImageCache.m
index 374eeac653..68469303e3 100644
--- a/UIKit+AFNetworking/AFAutoPurgingImageCache.m
+++ b/UIKit+AFNetworking/AFAutoPurgingImageCache.m
@@ -28,7 +28,7 @@
 @interface AFCachedImage : NSObject
 
 @property (nonatomic, strong) UIImage *image;
-@property (nonatomic, strong) NSString *identifier;
+@property (nonatomic, copy) NSString *identifier;
 @property (nonatomic, assign) UInt64 totalBytes;
 @property (nonatomic, strong) NSDate *lastAccessDate;
 @property (nonatomic, assign) UInt64 currentMemoryUsage;