diff --git a/news/2450.bugfix b/news/2450.bugfix
new file mode 100644
index 00000000..b9372832
--- /dev/null
+++ b/news/2450.bugfix
@@ -0,0 +1 @@
+Pipenv will now ensure that its internal package names registry files are written with unicode strings.
diff --git a/pipenv/project.py b/pipenv/project.py
index db515acf..d13f6491 100644
--- a/pipenv/project.py
+++ b/pipenv/project.py
@@ -363,7 +363,7 @@ class Project(object):
     def register_proper_name(self, name):
         """Registers a proper name to the database."""
         with self.proper_names_db_path.open('a') as f:
-            f.write('{0}\n'.format(name))
+            f.write(u'{0}\n'.format(name))
 
     @property
     def pipfile_location(self):