diff --git a/Lib/test/test_zipfile.py b/Lib/test/test_zipfile.py
index 61c3e34..ac9a4ff 100644
--- a/Lib/test/test_zipfile.py
+++ b/Lib/test/test_zipfile.py
@@ -1646,6 +1646,8 @@
                 self.assertEqual(fp.read(5), txt[bloc:bloc+5])
                 fp.seek(0, os.SEEK_END)
                 self.assertEqual(fp.tell(), len(txt))
+                fp.seek(0, os.SEEK_SET)
+                self.assertEqual(fp.tell(), 0)
         # Check seek on memory file
         data = io.BytesIO()
         with zipfile.ZipFile(data, mode="w") as zipf:
@@ -1661,6 +1663,8 @@
                 self.assertEqual(fp.read(5), txt[bloc:bloc+5])
                 fp.seek(0, os.SEEK_END)
                 self.assertEqual(fp.tell(), len(txt))
+                fp.seek(0, os.SEEK_SET)
+                self.assertEqual(fp.tell(), 0)
 
     def tearDown(self):
         unlink(TESTFN)
diff --git a/Lib/zipfile.py b/Lib/zipfile.py
index b90b60f..2757ce9 100644
--- a/Lib/zipfile.py
+++ b/Lib/zipfile.py
@@ -701,11 +701,11 @@
 
     def seek(self, offset, whence=0):
         with self._lock:
-            if self.writing():
+            if self._writing():
                 raise ValueError("Can't reposition in the ZIP file while "
                         "there is an open writing handle on it. "
                         "Close the writing handle before trying to read.")
-            self._file.seek(self._pos)
+            self._file.seek(offset, whence)
             self._pos = self._file.tell()
             return self._pos
 
@@ -1021,14 +1021,13 @@
             read_offset = 0
         elif read_offset < 0:
             # Position is before the current position. Reset the ZipExtFile
-
             self._fileobj.seek(self._orig_compress_start)
             self._running_crc = self._orig_start_crc
             self._compress_left = self._orig_compress_size
             self._left = self._orig_file_size
             self._readbuffer = b''
             self._offset = 0
-            self._decompressor = zipfile._get_decompressor(self._compress_type)
+            self._decompressor = _get_decompressor(self._compress_type)
             self._eof = False
             read_offset = new_pos