diff --git a/SSZipArchive/SSZipArchive.h b/SSZipArchive/SSZipArchive.h
index 8c4b8b2..708ca16 100755
--- a/SSZipArchive/SSZipArchive.h
+++ b/SSZipArchive/SSZipArchive.h
@@ -40,14 +40,14 @@ NS_ASSUME_NONNULL_BEGIN
 + (BOOL)unzipFileAtPath:(NSString *)path
     toDestination:(NSString *)destination
     progressHandler:(void (^)(NSString *entry, unz_file_info zipInfo, long entryNumber, long total))progressHandler
-    completionHandler:(void (^)(NSString *path, BOOL succeeded, NSError *error))completionHandler;
+    completionHandler:(void (^)(NSString *path, BOOL succeeded, NSError * __nullable error))completionHandler;
 
 + (BOOL)unzipFileAtPath:(NSString *)path
     toDestination:(NSString *)destination
     overwrite:(BOOL)overwrite
     password:(nullable NSString *)password
     progressHandler:(void (^)(NSString *entry, unz_file_info zipInfo, long entryNumber, long total))progressHandler
-    completionHandler:(void (^)(NSString *path, BOOL succeeded, NSError *error))completionHandler;
+    completionHandler:(void (^)(NSString *path, BOOL succeeded, NSError * __nullable error))completionHandler;
 
 // Zip
 
diff --git a/SSZipArchive/SSZipArchive.m b/SSZipArchive/SSZipArchive.m
index 22009d4..1960b64 100755
--- a/SSZipArchive/SSZipArchive.m
+++ b/SSZipArchive/SSZipArchive.m
@@ -155,7 +155,7 @@
               overwrite:(BOOL)overwrite
                password:(NSString *)password
         progressHandler:(void (^)(NSString *entry, unz_file_info zipInfo, long entryNumber, long total))progressHandler
-      completionHandler:(void (^)(NSString *path, BOOL succeeded, NSError *error))completionHandler
+      completionHandler:(void (^)(NSString *path, BOOL succeeded, NSError *__nullable error))completionHandler
 {
     return [self unzipFileAtPath:path toDestination:destination preserveAttributes:YES overwrite:overwrite password:password error:nil delegate:nil progressHandler:progressHandler completionHandler:completionHandler];
 }
@@ -163,7 +163,7 @@
 + (BOOL)unzipFileAtPath:(NSString *)path
           toDestination:(NSString *)destination
         progressHandler:(void (^)(NSString *entry, unz_file_info zipInfo, long entryNumber, long total))progressHandler
-      completionHandler:(void (^)(NSString *path, BOOL succeeded, NSError *error))completionHandler
+      completionHandler:(void (^)(NSString *path, BOOL succeeded, NSError * __nullable error))completionHandler
 {
     return [self unzipFileAtPath:path toDestination:destination preserveAttributes:YES overwrite:YES password:nil error:nil delegate:nil progressHandler:progressHandler completionHandler:completionHandler];
 }
@@ -187,7 +187,7 @@
                   error:(NSError **)error
                delegate:(id<SSZipArchiveDelegate>)delegate
         progressHandler:(void (^)(NSString *entry, unz_file_info zipInfo, long entryNumber, long total))progressHandler
-      completionHandler:(void (^)(NSString *path, BOOL succeeded, NSError *error))completionHandler
+      completionHandler:(void (^)(NSString *path, BOOL succeeded, NSError * __nullable error))completionHandler
 {
     // Begin opening
     zipFile zip = unzOpen((const char*)[path UTF8String]);