diff --git a/pipenv/project.py b/pipenv/project.py
index 7b5f1592..1b1b7142 100644
--- a/pipenv/project.py
+++ b/pipenv/project.py
@@ -14,7 +14,7 @@ import toml
 from .utils import (
     mkdir_p, convert_deps_from_pip, pep423_name, recase_file,
     find_requirements, is_file, is_vcs, python_version, cleanup_toml,
-    is_installable_file, is_valid_url
+    is_installable_file, is_valid_url, normalize_drive,
 )
 from .environments import PIPENV_MAX_DEPTH, PIPENV_VENV_IN_PROJECT
 from .environments import PIPENV_VIRTUALENV, PIPENV_PIPFILE
@@ -23,7 +23,7 @@ if PIPENV_PIPFILE:
     if not os.path.isfile(PIPENV_PIPFILE):
         raise RuntimeError('Given PIPENV_PIPFILE is not found!')
     else:
-        PIPENV_PIPFILE = os.path.abspath(PIPENV_PIPFILE)
+        PIPENV_PIPFILE = normalize_drive(os.path.abspath(PIPENV_PIPFILE))
 
 
 class Project(object):
@@ -224,7 +224,7 @@ class Project(object):
                 loc = pipfile.Pipfile.find(max_depth=PIPENV_MAX_DEPTH)
             except RuntimeError:
                 loc = None
-            self._pipfile_location = loc
+            self._pipfile_location = normalize_drive(loc)
 
         return self._pipfile_location
 
diff --git a/pipenv/utils.py b/pipenv/utils.py
index 90a774e9..f42e1fac 100644
--- a/pipenv/utils.py
+++ b/pipenv/utils.py
@@ -277,7 +277,7 @@ def get_requirement(dep):
     remote URIs, and package names, and that we pass only valid requirement strings
     to the requirements parser. Performs necessary modifications to requirements
     object if the user input was a local relative path.
-    
+
     :param str dep: A requirement line
     :returns: :class:`requirements.Requirement` object
     """
@@ -932,11 +932,11 @@ def proper_case(package_name):
 def split_section(input_file, section_suffix, test_function):
     """
     Split a pipfile or a lockfile section out by section name and test function
-    
+
         :param dict input_file: A dictionary containing either a pipfile or lockfile
         :param str section_suffix: A string of the name of the section
         :param func test_function: A test function to test against the value in the key/value pair
-    
+
     >>> split_section(my_lockfile, 'vcs', is_vcs)
     {
         'default': {
@@ -992,7 +992,7 @@ def merge_deps(file_dict, project, dev=False, requirements=False, ignore_hashes=
     Given a file_dict, merges dependencies and converts them to pip dependency lists.
         :param dict file_dict: The result of calling :func:`pipenv.utils.split_file`
         :param :class:`pipenv.project.Project` project: Pipenv project
-        :param bool dev=False: Flag indicating whether dev dependencies are to be installed 
+        :param bool dev=False: Flag indicating whether dev dependencies are to be installed
         :param bool requirements=False: Flag indicating whether to use a requirements file
         :param bool ignore_hashes=False:
         :param bool blocking=False:
@@ -1174,3 +1174,21 @@ def touch_update_stamp():
     except OSError:
         with open(p, 'w') as fh:
             fh.write('')
+
+
+def normalize_drive(path):
+    """Normalize drive in path so they stay consistent.
+
+    This currently only affects local drives on Windows, which can be
+    identified with either upper or lower cased drive names. The case is
+    always converted to uppercase because it seems to be preferred.
+
+    See: <https://github.com/pypa/pipenv/issues/1218>
+    """
+    if os.name != 'nt':
+        return path
+    drive, tail = os.path.splitdrive(path)
+    # Only match (lower cased) local drives (e.g. 'c:'), not UNC mounts.
+    if drive.islower() and len(drive) == 2 and drive[1] == ':':
+        return '{}{}'.format(drive.upper(), tail)
+    return path
diff --git a/tests/test_utils.py b/tests/test_utils.py
index ffb875ef..f570a631 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -226,3 +226,27 @@ twine = "*"
         new_toml = pipenv.utils.cleanup_toml(toml)
         # testing if the end of the generated file contains a newline
         assert new_toml[-1] == '\n'
+
+    @pytest.mark.parametrize('input_path, expected', [
+        ('c:\\Program Files\\Python36\\python.exe',
+         'C:\\Program Files\\Python36\\python.exe'),
+        ('C:\\Program Files\\Python36\\python.exe',
+         'C:\\Program Files\\Python36\\python.exe'),
+        ('\\\\host\\share\\file.zip', '\\\\host\\share\\file.zip'),
+        ('artifacts\\file.zip', 'artifacts\\file.zip'),
+        ('.\\artifacts\\file.zip', '.\\artifacts\\file.zip'),
+        ('..\\otherproject\\file.zip', '..\\otherproject\\file.zip'),
+    ])
+    @pytest.mark.skipif(os.name != 'nt', reason='Windows file paths tested')
+    def test_win_normalize_drive(self, input_path, expected):
+        assert pipenv.utils.normalize_drive(input_path) == expected
+
+    @pytest.mark.parametrize('input_path, expected', [
+        ('/usr/local/bin/python', '/usr/local/bin/python'),
+        ('artifacts/file.zip', 'artifacts/file.zip'),
+        ('./artifacts/file.zip', './artifacts/file.zip'),
+        ('../otherproject/file.zip', '../otherproject/file.zip'),
+    ])
+    @pytest.mark.skipif(os.name == 'nt', reason='*nix file paths tested')
+    def test_nix_normalize_drive(self, input_path, expected):
+        assert pipenv.utils.normalize_drive(input_path) == expected