diff --git a/pipenv/cli.py b/pipenv/cli.py
index 712178b0..9cc591dd 100644
--- a/pipenv/cli.py
+++ b/pipenv/cli.py
@@ -269,6 +269,18 @@ def ensure_pipfile(validate=True):
             # Import requirements.txt.
             import_requirements()
 
+            # Warn the user of side-effects.
+            click.echo(
+                u'{0}: Your {1} now contains pinned versions, if your {2} did. \n'
+                'We recommend updating your {1} to specify the {3} version, instead.'
+                ''.format(
+                    crayons.red('Warning', bold=True),
+                    crayons.white('Pipfile', bold=True),
+                    crayons.white('requirements.txt', bold=True),
+                    crayons.white('"*"', bold=True)
+                )
+            )
+
         else:
             puts(crayons.white(u'Creating a Pipfile for this project…', bold=True), err=True)
 
@@ -289,6 +301,7 @@ def ensure_pipfile(validate=True):
 
 
 def find_a_system_python(python):
+    """Finds a system python, given a version (e.g. 2.7 / 3.6), or a full path."""
     if python.startswith('py'):
         return system_which(python)
     elif os.path.isabs(python):
@@ -398,7 +411,7 @@ def ensure_project(three=None, python=None, validate=True, system=False, warn=Tr
 
                 path_to_python = which('python')
 
-                if project.required_python_version not in python_version(path_to_python):
+                if project.required_python_version not in (python_version(path_to_python) or ''):
                     puts(
                         '{0}: Your Pipfile requires {1} {2}, '
                         'but you are using {3} ({4}).'.format(
diff --git a/pipenv/utils.py b/pipenv/utils.py
index 725a7ffd..2e713915 100644
--- a/pipenv/utils.py
+++ b/pipenv/utils.py
@@ -29,7 +29,6 @@ def python_version(path_to_python):
     try:
         TEMPLATE = 'Python {}.{}.{}'
         c = delegator.run([path_to_python, '--version'], block=False)
-        assert c.return_code == 0
     except Exception:
         return None
 
@@ -56,7 +55,7 @@ class HackedPythonVersion(object):
 
     def __enter__(self):
         if self.python:
-            os.environ['PIP_PYTHON_VERSION'] = self.python
+            os.environ['PIP_PYTHON_VERSION'] = str(self.python)
 
     def __exit__(self, *args):
         # Restore original Python version information.
diff --git a/test_windows/test_pipenv.py b/test_windows/test_pipenv.py
index 3ade112d..c98d36fd 100644
--- a/test_windows/test_pipenv.py
+++ b/test_windows/test_pipenv.py
@@ -4,19 +4,32 @@ import shutil
 from mock import patch, Mock, PropertyMock
 
 import delegator
-import toml
+from pipenv.patched import contoml
 
 from pipenv.cli import (
     ensure_proper_casing,
-    pip_install, pip_download
+    pip_install, pip_download, find_a_system_python
 )
 
+FULL_PYTHON_PATH = 'C:\\Python36-x64\\python.exe'
 
 class TestPipenvWindows():
 
     def test_existience(self):
         assert True
 
+    def test_cli_with_custom_python_path(self):
+        delegator.run('mkdir custom_python')
+        os.chdir('custom_python')
+
+        c = delegator.run('pipenv install --python={0}'.format(FULL_PYTHON_PATH))
+
+        # Debugging, if it fails.
+        print(c.out)
+        print(c.err)
+
+        assert c.return_code == 0
+
     def test_cli_usage(self):
         delegator.run('mkdir test_project')
         os.chdir('test_project')
@@ -187,7 +200,7 @@ class TestPipenvWindows():
                       "PyTEST = \"*\"\n")
 
         # Load test Pipfile.
-        p = toml.loads(pfile_test)
+        p = contoml.loads(pfile_test)
 
         assert 'DjAnGO' in p['packages']
         assert 'PyTEST' in p['dev-packages']
diff --git a/test_windows/test_utils.py b/test_windows/test_utils.py
new file mode 100644
index 00000000..6a02170e
--- /dev/null
+++ b/test_windows/test_utils.py
@@ -0,0 +1,14 @@
+import delegator
+
+from pipenv.utils import python_version
+
+
+FULL_PYTHON_PATH = 'C:\\Python36-x64\\python.exe'
+
+
+class TestUtilsWindows():
+
+    def test_python_version_from_full_path(self):
+        print(delegator.run('{0} --version'.format(FULL_PYTHON_PATH)).out)
+
+        assert python_version(FULL_PYTHON_PATH) == "3.6.1"
diff --git a/tests/test_utils.py b/tests/test_utils.py
index 29d26e5d..a054ca24 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -138,15 +138,16 @@ class TestUtils:
 
     def test_split_vcs(self):
         pipfile_dict = {
-                        'packages': {
-                            'requests': {'git': 'https://github.com/kennethreitz/requests.git'},
-                            'Flask': '*'
-                        },
-                        'dev-packages': {
-                            'Django': '==1.10',
-                            'click': {'svn': 'https://svn.notareal.com/click'},
-                            'crayons': {'hg': 'https://hg.alsonotreal.com/crayons'}
-                        }}
+            'packages': {
+                'requests': {'git': 'https://github.com/kennethreitz/requests.git'},
+                'Flask': '*'
+            },
+            'dev-packages': {
+                'Django': '==1.10',
+                'click': {'svn': 'https://svn.notareal.com/click'},
+                'crayons': {'hg': 'https://hg.alsonotreal.com/crayons'}
+            }
+        }
         split_dict = pipenv.utils.split_vcs(pipfile_dict)
 
         assert list(split_dict['packages'].keys()) == ['Flask']
@@ -154,3 +155,9 @@ class TestUtils:
         assert list(split_dict['dev-packages'].keys()) == ['Django']
         assert 'click' in split_dict['dev-packages-vcs']
         assert 'crayons' in split_dict['dev-packages-vcs']
+
+    def test_python_version_from_bad_path(self):
+        assert pipenv.utils.python_version("/fake/path") is None
+
+    def test_python_version_from_non_python(self):
+        assert pipenv.utils.python_version("/dev/null") is None