diff --git a/archive.py b/archive.py
index eaa6448..f0917de 100644
--- a/archive.py
+++ b/archive.py
@@ -76,7 +76,7 @@ class ArchiveSender:
 
 
 class TarSender(ArchiveSender):
-    def response(self):
+    def generator(self):
         def generate():
             for name, file in self.files.items():
                 yield tar_header_chunk(name, file)
@@ -96,9 +96,11 @@ class TarSender(ArchiveSender):
                     # Because tar use records of 512 bytes, we need to pad the
                     # file with zeroes to fill the last chunk
                     yield b'\x00' * (512 - bytes_sent % 512)
+        return generate()
 
+    def response(self):
         return Response(
-            generate(),
+            self.generator(),
             mimetype='application/x-tar',
             headers={'Content-Disposition': 'attachment; filename="archive.tar"'}
         )
@@ -131,9 +133,9 @@ def zip_local_file_header(filename: str, filepath: str) -> bytes:
     # Field 4: compression mode (buffer[8:10]), leave at 0 (uncompressed)
 
     # Field 5: file last modification time (buffer[10:14])
-    mtime = datetime.fromtimestramp(stat.st_mtime)
-    buffer[10:12] = (mtime.second // 2) | (mtime.minute << 5) | (mtime.hour << 11)
-    buffer[12:14] = mtime.day | (mtime.month << 5) | ((mtime.year - 1980) << 9)
+    mtime = datetime.fromtimestamp(stat.st_mtime)
+    buffer[10:12] = ((mtime.second // 2) | (mtime.minute << 5) | (mtime.hour << 11)).to_bytes(2, byteorder='little')
+    buffer[12:14] = (mtime.day | (mtime.month << 5) | ((mtime.year - 1980) << 9)).to_bytes(2, byteorder='little')
 
     # Field 6: crc-32 of uncompressed data (buffer[14:18])
     buffer[14:18] = crc32(filepath).to_bytes(4, byteorder='little')
@@ -161,7 +163,7 @@ def zip_central_directory_file_header(filename: str, filepath: str, offset: int)
     stat = os.stat(filepath)
 
     # Field 1: central directory file header signature (buffer[0:4])
-    buffer[0:4] = b'\x02\x01\x4b\x50'
+    buffer[0:4] = b'\x50\x4b\x01\x02'
 
     # Field 2: version made by (buffer[4:6])
     buffer[4:6] = b'\x0a'
@@ -174,9 +176,9 @@ def zip_central_directory_file_header(filename: str, filepath: str, offset: int)
     # Field 4: compression mode (buffer[10:12]), leave at 0 (uncompressed)
 
     # Field 5: file last modification time (buffer[12:16])
-    mtime = datetime.fromtimestramp(stat.st_mtime)
-    buffer[12:14] = (mtime.second // 2) | (mtime.minute << 5) | (mtime.hour << 11)
-    buffer[14:16] = mtime.day | (mtime.month << 5) | ((mtime.year - 1980) << 9)
+    mtime = datetime.fromtimestamp(stat.st_mtime)
+    buffer[12:14] = ((mtime.second // 2) | (mtime.minute << 5) | (mtime.hour << 11)).to_bytes(2, byteorder='little')
+    buffer[14:16] = (mtime.day | (mtime.month << 5) | ((mtime.year - 1980) << 9)).to_bytes(2, byteorder='little')
 
     # Field 6: crc-32 of uncompressed data (buffer[16:20])
     buffer[16:20] = crc32(filepath).to_bytes(4, byteorder='little')
@@ -211,7 +213,7 @@ def zip_central_directory_file_header(filename: str, filepath: str, offset: int)
 def zip_end_of_central_directory(items_number: int, central_directory_size: int, central_directory_offset: int):
     buffer = bytearray(22)
     # Field 1: End of central directory signature = 0x06054b50 (buffer[0:4])
-    buffer[0:4] = b'\x06\x05\x4b\x50'
+    buffer[0:4] = b'\x50\x4b\x05\x06'
 
     # Field 2: Number of this disk (buffer[4:6])
 
@@ -236,7 +238,7 @@ def zip_end_of_central_directory(items_number: int, central_directory_size: int,
 
 
 class ZipSender(ArchiveSender):
-    def response(self):
+    def generator(self):
         def generate():
             local_offsets = dict()
             current_byte = 0
@@ -244,7 +246,7 @@ class ZipSender(ArchiveSender):
             for name, file in self.files.items():
                 local_offsets[name] = current_byte
                 chunk = zip_local_file_header(name, file)
-                current_byte += chunk
+                current_byte += len(chunk)
 
                 yield chunk
 
@@ -269,8 +271,11 @@ class ZipSender(ArchiveSender):
 
             yield zip_end_of_central_directory(len(self.files.items()), central_directory_size, centra_directory_offset)
 
+        return generate()
+
+    def response(self):
         return Response(
-            generate(),
+            self.generator(),
             mimetype='application/zip',
             headers={'Content-Disposition': 'attachment; filename="archive.zip"'}
         )