diff --git a/docx/opc/phys_pkg.py b/docx/opc/phys_pkg.py
index c86a51994..8db7e5cfe 100644
--- a/docx/opc/phys_pkg.py
+++ b/docx/opc/phys_pkg.py
@@ -8,7 +8,7 @@
 
 import os
 
-from zipfile import ZipFile, is_zipfile, ZIP_DEFLATED
+from zipfile import ZipFile, ZipInfo, is_zipfile, ZIP_DEFLATED
 
 from .compat import is_string
 from .exceptions import PackageNotFoundError
@@ -152,4 +152,5 @@ def write(self, pack_uri, blob):
         Write *blob* to this zip package with the membername corresponding to
         *pack_uri*.
         """
-        self._zipf.writestr(pack_uri.membername, blob)
+        zinfo = ZipInfo(filename=pack_uri.membername, date_time=(1980, 1, 1, 0, 0, 0))
+        self._zipf.writestr(zinfo, blob)
diff --git a/docx/opc/pkgwriter.py b/docx/opc/pkgwriter.py
index fccda6cd8..b557b53ea 100644
--- a/docx/opc/pkgwriter.py
+++ b/docx/opc/pkgwriter.py
@@ -30,9 +30,10 @@ def write(pkg_file, pkg_rels, parts):
         content types of the parts.
         """
         phys_writer = PhysPkgWriter(pkg_file)
-        PackageWriter._write_content_types_stream(phys_writer, parts)
+        sorted_parts = sorted(parts, key=lambda p: p.partname)
+        PackageWriter._write_content_types_stream(phys_writer, sorted_parts)
         PackageWriter._write_pkg_rels(phys_writer, pkg_rels)
-        PackageWriter._write_parts(phys_writer, parts)
+        PackageWriter._write_parts(phys_writer, sorted_parts)
         phys_writer.close()
 
     @staticmethod
diff --git a/docx/opc/rel.py b/docx/opc/rel.py
index 7dba2af8e..cd719d5fd 100644
--- a/docx/opc/rel.py
+++ b/docx/opc/rel.py
@@ -78,7 +78,7 @@ def xml(self):
         as a .rels file in an OPC package.
         """
         rels_elm = CT_Relationships.new()
-        for rel in self.values():
+        for rel in sorted(self.values(), key=lambda r: r._rId):
             rels_elm.add_rel(
                 rel.rId, rel.reltype, rel.target_ref, rel.is_external
             )