diff --git a/poetry/masonry/builders/wheel.py b/poetry/masonry/builders/wheel.py
index d920294bfb4..bc83050e952 100644
--- a/poetry/masonry/builders/wheel.py
+++ b/poetry/masonry/builders/wheel.py
@@ -2,6 +2,7 @@
 
 import contextlib
 import hashlib
+import io
 import os
 import re
 import tempfile
@@ -233,7 +234,7 @@ def _add_file(self, wheel, full_path, rel_path):
             zinfo.external_attr |= 0x10  # MS-DOS directory flag
 
         hashsum = hashlib.sha256()
-        with open(full_path, "rb") as src:
+        with io.open(full_path, "rb") as src:
             while True:
                 buf = src.read(1024 * 8)
                 if not buf:
diff --git a/poetry/repositories/legacy_repository.py b/poetry/repositories/legacy_repository.py
index d8c16242e3b..72c38b74332 100644
--- a/poetry/repositories/legacy_repository.py
+++ b/poetry/repositories/legacy_repository.py
@@ -1,4 +1,5 @@
 import cgi
+import io
 import re
 
 try:
@@ -341,7 +342,7 @@ def _get_release_info(self, name, version):  # type: (str, str) -> dict
 
     def _download(self, url, dest):  # type: (str, str) -> None
         r = self._session.get(url, stream=True)
-        with open(dest, "wb") as f:
+        with io.open(dest, "wb") as f:
             for chunk in r.iter_content(chunk_size=1024):
                 if chunk:
                     f.write(chunk)
diff --git a/poetry/repositories/pypi_repository.py b/poetry/repositories/pypi_repository.py
index 990d8b12f59..756366c3279 100644
--- a/poetry/repositories/pypi_repository.py
+++ b/poetry/repositories/pypi_repository.py
@@ -1,4 +1,5 @@
 import logging
+import io
 import os
 import re
 import tarfile
@@ -512,7 +513,7 @@ def _inspect_sdist_with_setup(self, sdist_dir):
 
     def _download(self, url, dest):  # type: (str, str) -> None
         r = get(url, stream=True)
-        with open(dest, "wb") as f:
+        with io.open(dest, "wb") as f:
             for chunk in r.iter_content(chunk_size=1024):
                 if chunk:
                     f.write(chunk)