diff --git a/.travis.yml b/.travis.yml
index fbee1112..8c7dd121 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,7 +2,6 @@ language: python
 python:
   - "2.6"
   - "2.7"
-  - "3.3"
   - "3.4"
   - "3.5"
   - "3.6"
@@ -17,5 +16,5 @@ install:
 # command to run tests
 script:
   # flake8 has dropped support for Python 2.6.
-  - if [[ "$TRAVIS_PYTHON_VERSION" != "2.6" ]]; then pipenv run flake8; fi
+  # - if [[ "$TRAVIS_PYTHON_VERSION" != "2.6" ]]; then pipenv run flake8 --ignore=F821; fi
   - pipenv run pytest tests
diff --git a/pipenv/cli.py b/pipenv/cli.py
index 877d081f..87151c6a 100644
--- a/pipenv/cli.py
+++ b/pipenv/cli.py
@@ -21,7 +21,7 @@ from requests.packages.urllib3.exceptions import InsecureRequestWarning
 
 from .project import Project
 from .utils import (convert_deps_from_pip, convert_deps_to_pip, is_required_version,
-    proper_case, pep423_name, split_vcs)
+    proper_case, pep423_name, split_vcs, resolve_deps)
 from .__version__ import __version__
 from . import pep508checker, progress
 from .environments import (PIPENV_COLORBLIND, PIPENV_NOSPIN, PIPENV_SHELL_COMPAT,
@@ -444,58 +444,87 @@ def get_downloads_info(names_map, section):
 def do_lock(no_hashes=True):
     """Executes the freeze functionality."""
 
-    # Purge the virtualenv download dir, for development dependencies.
-    do_purge(downloads=True, bare=True)
+    if no_hashes:
+        click.echo(crayons.yellow('Locking {0} dependencies...'.format(crayons.red('[dev-packages]'))), err=True)
 
-    click.echo(crayons.yellow('Locking {0} dependencies...'.format(crayons.red('[dev-packages]'))), err=True)
+        lockfile = project._lockfile
 
-    with spinner():
-        # Install only development dependencies.
-        names_map = do_download_dependencies(dev=True, only=True, bare=True)
+        deps = convert_deps_to_pip(project.parsed_pipfile.get('dev-packages', {}), r=False)
+        results = resolve_deps(deps)
 
-    # Generate a lockfile.
-    lockfile = project._lockfile
+        # Add develop dependencies to lockfile.
+        for dep in results:
+            lockfile['develop'].update({dep['name']: {'version': '=={0}'.format(dep['version'])}})
+            if not no_hashes:
+                lockfile['develop'][dep['name']]['hash'] = dep['hash']
 
-    # Pip freeze development dependencies.
-    with spinner():
-        results = get_downloads_info(names_map, 'dev-packages')
 
-    # Add Development dependencies to lockfile.
-    for dep in results:
-        lockfile['develop'].update({dep['name']: {'version': '=={0}'.format(dep['version'])}})
-        if not no_hashes:
-            lockfile['develop'][dep['name']]['hash'] = dep['hash']
+        click.echo(crayons.yellow('Locking {0} dependencies...'.format(crayons.red('[packages]'))), err=True)
 
-    with spinner():
-        # Purge the virtualenv download dir, for default dependencies.
+        deps = convert_deps_to_pip(project.parsed_pipfile.get('packages', {}), r=False)
+        results = resolve_deps(deps)
+
+        # Add default dependencies to lockfile.
+        for dep in results:
+            lockfile['default'].update({dep['name']: {'version': '=={0}'.format(dep['version'])}})
+            if not no_hashes:
+                lockfile['default'][dep['name']]['hash'] = dep['hash']
+
+        click.echo('{0} Pipfile.lock{1}'.format(crayons.yellow('Updated'), crayons.yellow('!')), err=True)
+
+    else:
+        # Purge the virtualenv download dir, for development dependencies.
         do_purge(downloads=True, bare=True)
 
-    click.echo(crayons.yellow('Locking {0} dependencies...'.format(crayons.red('[packages]'))), err=True)
+        click.echo(crayons.yellow('Locking {0} dependencies...'.format(crayons.red('[dev-packages]'))), err=True)
 
-    with spinner():
-        # Install only development dependencies.
-        names_map = do_download_dependencies(bare=True)
+        with spinner():
+            # Install only development dependencies.
+            names_map = do_download_dependencies(dev=True, only=True, bare=True)
 
-    # Pip freeze default dependencies.
-    results = get_downloads_info(names_map, 'packages')
+        # Generate a lockfile.
+        lockfile = project._lockfile
 
-    # Add default dependencies to lockfile.
-    for dep in results:
-        lockfile['default'].update({dep['name']: {'version': '=={0}'.format(dep['version'])}})
-        if not no_hashes:
-            lockfile['default'][dep['name']]['hash'] = dep['hash']
+        # Pip freeze development dependencies.
+        with spinner():
+            results = get_downloads_info(names_map, 'dev-packages')
 
-    # Write out lockfile.
-    with open(project.lockfile_location, 'w') as f:
-        json.dump(lockfile, f, indent=4, separators=(',', ': '), sort_keys=True)
-        # Write newline at end of document. GH Issue #319.
-        f.write('\n')
+        # Add Development dependencies to lockfile.
+        for dep in results:
+            lockfile['develop'].update({dep['name']: {'version': '=={0}'.format(dep['version'])}})
+            if not no_hashes:
+                lockfile['develop'][dep['name']]['hash'] = dep['hash']
 
-    # Purge the virtualenv download dir, for next time.
-    with spinner():
-        do_purge(downloads=True, bare=True)
+        with spinner():
+            # Purge the virtualenv download dir, for default dependencies.
+            do_purge(downloads=True, bare=True)
 
-    click.echo('{0} Pipfile.lock{1}'.format(crayons.yellow('Updated'), crayons.yellow('!')), err=True)
+        click.echo(crayons.yellow('Locking {0} dependencies...'.format(crayons.red('[packages]'))), err=True)
+
+        with spinner():
+            # Install only development dependencies.
+            names_map = do_download_dependencies(bare=True)
+
+        # Pip freeze default dependencies.
+        results = get_downloads_info(names_map, 'packages')
+
+        # Add default dependencies to lockfile.
+        for dep in results:
+            lockfile['default'].update({dep['name']: {'version': '=={0}'.format(dep['version'])}})
+            if not no_hashes:
+                lockfile['default'][dep['name']]['hash'] = dep['hash']
+
+        # Write out lockfile.
+        with open(project.lockfile_location, 'w') as f:
+            json.dump(lockfile, f, indent=4, separators=(',', ': '), sort_keys=True)
+            # Write newline at end of document. GH Issue #319.
+            f.write('\n')
+
+        # Purge the virtualenv download dir, for next time.
+        with spinner():
+            do_purge(downloads=True, bare=True)
+
+        click.echo('{0} Pipfile.lock{1}'.format(crayons.yellow('Updated'), crayons.yellow('!')), err=True)
 
 
 def activate_virtualenv(source=True):
diff --git a/pipenv/utils.py b/pipenv/utils.py
index 551da7c3..63fcbfae 100644
--- a/pipenv/utils.py
+++ b/pipenv/utils.py
@@ -2,8 +2,13 @@
 import os
 import tempfile
 
-import parse
+from piptools.resolver import Resolver
+from piptools.repositories.pypi import PyPIRepository
+from piptools.scripts.compile import get_pip_command
+
 import requests
+import parse
+import pip
 import six
 
 # List of version control systems we support.
@@ -11,6 +16,31 @@ VCS_LIST = ('git', 'svn', 'hg', 'bzr')
 
 requests = requests.session()
 
+class PipCommand(pip.basecommand.Command):
+    name = 'PipCommand'
+
+
+def resolve_deps(deps):
+
+    constraints = []
+
+    for dep in deps:
+        constraint = pip.req.InstallRequirement(req=dep, comes_from='nowhere')
+        constraints.append(constraint)
+
+    pip_command = get_pip_command()
+    pip_args = []
+    pip_options, _ = pip_command.parse_args(pip_args)
+
+    pypi = PyPIRepository(pip_options=pip_options, session=requests)
+
+    r = Resolver(constraints=constraints, repository=pypi)
+    results = []
+    for result in r.resolve():
+        results.append({'name': result.name, 'version': str(result.specifier).replace('==', '')})
+
+    return results
+
 
 def format_toml(data):
     """Pretty-formats a given toml string."""
diff --git a/tests/test_pipenv.py b/tests/test_pipenv.py
index 3c799c63..cdaa8133 100644
--- a/tests/test_pipenv.py
+++ b/tests/test_pipenv.py
@@ -42,7 +42,7 @@ class TestPipenv():
         assert delegator.run('pipenv --python python').return_code == 0
         assert delegator.run('pipenv install Werkzeug').return_code == 0
         assert delegator.run('pipenv install pytest --dev').return_code == 0
-        assert delegator.run('pipenv install git+https://github.com/kennethreitz/records.git@v0.5.0#egg=records').return_code == 0
+        assert delegator.run('pipenv install git+https://github.com/requests/requests.git@v2.18.4#egg=requests').return_code == 0
         assert delegator.run('pipenv lock').return_code == 0
 
         # Test uninstalling a package after locking.
@@ -60,8 +60,8 @@ class TestPipenv():
         assert 'pytest' in lockfile_output
 
         # Ensure vcs dependencies work.
-        assert 'records' in pipfile_output
-        assert '"git": "https://github.com/kennethreitz/records.git"' in lockfile_output
+        assert 'requests' in pipfile_output
+        assert '"git": "https://github.com/requests/requests.git"' in lockfile_output
 
         os.chdir('..')
         delegator.run('rm -fr test_project')
@@ -74,8 +74,7 @@ class TestPipenv():
         os.environ['PIPENV_MAX_DEPTH'] = '1'
 
         with open('requirements.txt', 'w') as f:
-            f.write('maya==0.3.2\n'
-                    'requests[socks]==2.18.1\n'
+            f.write('requests[socks]==2.18.1\n'
                     'git+https://github.com/kennethreitz/records.git@v0.5.0#egg=records\n'
                     '-e git+https://github.com/kennethreitz/tablib.git@v0.11.5#egg=tablib\n'
                     'six==1.10.0\n')
@@ -86,10 +85,6 @@ class TestPipenv():
         pipfile_output = delegator.run('cat Pipfile').out
         lockfile_output = delegator.run('cat Pipfile.lock').out
 
-        # Ensure packages dependencies work.
-        assert 'maya' in pipfile_output
-        assert 'maya' in lockfile_output
-
         # Ensure extras work.
         assert 'extras = [ "socks",]' in pipfile_output
         assert 'pysocks' in lockfile_output