diff --git a/.gitmodules b/.gitmodules
index c0d2229..604bd56 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,3 @@
 [submodule "zlib"]
 	path = zlib
-	url = https://github.com/madler/zlib.git
+	url = https://github.com/cielavenir/zlib.git
diff --git a/tests/test_deflate64.py b/tests/test_deflate64.py
index 92e1f6f..f7dc676 100644
--- a/tests/test_deflate64.py
+++ b/tests/test_deflate64.py
@@ -38,15 +38,18 @@ def test_decompress_output_type(data_dir, deflate64):
 
 
 def test_decompress_repeated(data_dir, deflate64):
-    """Ensure that resources are properly shared by repeated invocations of Deflate64.decompress."""
-    with open(data_dir / '10_lines.deflate64', 'rb') as compressed_content_stream:
-        decompressed_content_10 = deflate64.decompress(compressed_content_stream.read())
-
-    with open(data_dir / '100_lines.deflate64', 'rb') as compressed_content_stream:
-        decompressed_content_100 = deflate64.decompress(compressed_content_stream.read())
-
-    assert len(decompressed_content_10) == 180
-    assert len(decompressed_content_100) == 1890
+    """Ensure that Deflate64.decompress can be called repeatedly on a compressed stream."""
+    read_size = 64 * 2 ** 10
+    decompressed_content = b''
+    with open(data_dir / '100k_lines.deflate64', 'rb') as compressed_content_stream:
+        while True:
+            compressed_content = compressed_content_stream.read(read_size)
+            if not compressed_content:
+                break
+            decompressed_content += deflate64.decompress(compressed_content)
+
+    assert len(decompressed_content) == 2188890
+    assert re.match(rb'^(?:Sample content \d+\.\n)+$', decompressed_content)
 
 
 def test_decompress_empty(deflate64):
diff --git a/tests/test_zipfile.py b/tests/test_zipfile.py
index 7e21598..326e7c0 100644
--- a/tests/test_zipfile.py
+++ b/tests/test_zipfile.py
@@ -35,13 +35,11 @@ def test_zipfile_compress_type(zip_file):
         assert zip_ext_file.compress_type == zipfile.ZIP_DEFLATED64
 
 
-@pytest.mark.xfail(raises=ValueError)
 def test_zipfile_extract(tmp_path, zip_file, file_name):
     zip_file.extract(file_name, path=tmp_path)
     assert (tmp_path / file_name).exists()
 
 
-@pytest.mark.xfail(raises=ValueError)
 def test_zipfile_extractall(tmp_path, zip_file):
     zip_file.extractall(path=tmp_path)
     assert len(list(tmp_path.iterdir())) == 4
@@ -62,7 +60,6 @@ def test_zipfile_read_short(zip_ext_file):
     assert decompressed_content == b'Sample content 0.\n'
 
 
-@pytest.mark.xfail(raises=ValueError)
 def test_zipfile_readline_repeated(zip_ext_file):
     while True:
         decompressed_content = zip_ext_file.readline()
diff --git a/zlib b/zlib
index cacf7f1..beaec8d 160000
--- a/zlib
+++ b/zlib
@@ -1 +1 @@
-Subproject commit cacf7f1d4e3d44d871b605da3b647f07d718623f
+Subproject commit beaec8dc39f5caa86e808611b10f2ea0ab8720c2