diff --git a/pipenv/cli.py b/pipenv/cli.py
index a089e3c8..6a2d4b1c 100644
--- a/pipenv/cli.py
+++ b/pipenv/cli.py
@@ -225,7 +225,8 @@ def uninstall(
 @click.option('--dev', '-d', is_flag=True, default=False, help="Generate output compatible with requirements.txt for the development dependencies.")
 @click.option('--clear', is_flag=True, default=False, help="Clear the dependency cache.")
 @click.option('--pre', is_flag=True, default=False, help=u"Allow pre–releases.")
-def lock(three=None, python=False, verbose=False, requirements=False, dev=False, clear=False, pre=False):
+@click.option('--keep-outdated', is_flag=True, default=False, help=u"Keep out–dated dependencies from being updated.")
+def lock(three=None, python=False, verbose=False, requirements=False, dev=False, clear=False, pre=False, keep_outdated=False):
     from . import core
     # Ensure that virtualenv is available.
     core.ensure_project(three=three, python=python)
@@ -237,7 +238,7 @@ def lock(three=None, python=False, verbose=False, requirements=False, dev=False,
     if requirements:
         core.do_init(dev=dev, requirements=requirements)
 
-    core.do_lock(verbose=verbose, clear=clear, pre=pre)
+    core.do_lock(verbose=verbose, clear=clear, pre=pre, keep_outdated=keep_outdated)
 
 
 
diff --git a/pipenv/core.py b/pipenv/core.py
index e36f7ef1..4695a448 100644
--- a/pipenv/core.py
+++ b/pipenv/core.py
@@ -34,7 +34,7 @@ from .utils import (
     proper_case, pep423_name, split_file, merge_deps, resolve_deps, shellquote, is_vcs,
     python_version, find_windows_executable, is_file, prepare_pip_source_args,
     temp_environ, is_valid_url, download_file, get_requirement, need_update_check,
-    touch_update_stamp
+    touch_update_stamp, is_pinned
 )
 from .__version__ import __version__
 from . import pep508checker, progress
@@ -1009,9 +1009,18 @@ def get_downloads_info(names_map, section):
     return info
 
 
-def do_lock(verbose=False, system=False, clear=False, pre=False):
+def do_lock(verbose=False, system=False, clear=False, pre=False, keep_outdated=False):
     """Executes the freeze functionality."""
 
+    cached_lockfile = {}
+    if keep_outdated:
+        if not project.lockfile_exists:
+            click.echo('{0}: Pipfile.lock must exist to use --keep-outdated!'.format(
+                crayons.red('Warning', bold=True)
+            ))
+            sys.exit(1)
+        cached_lockfile = project.lockfile_content
+
     project.destroy_lockfile()
 
     # Alert the user of progress.
@@ -1152,6 +1161,13 @@ def do_lock(verbose=False, system=False, clear=False, pre=False):
             except IndexError:
                 pass
 
+    # Support for --keep-outdated…
+    if keep_outdated:
+        for section_name, section in (('default', project.packages), ('develop', project.dev_packages)):
+            for package_specified in section:
+                if not is_pinned(section[package_specified]):
+                    lockfile[section_name][package_specified] = cached_lockfile[section_name][package_specified]
+
     # Run the PEP 508 checker in the virtualenv, add it to the lockfile.
     cmd = '"{0}" {1}'.format(which('python', allow_global=system), shellquote(pep508checker.__file__.rstrip('cdo')))
     c = delegator.run(cmd)
diff --git a/pipenv/utils.py b/pipenv/utils.py
index ebe1d939..9e41a0c0 100644
--- a/pipenv/utils.py
+++ b/pipenv/utils.py
@@ -515,15 +515,17 @@ def convert_deps_from_pip(dep):
                 del dependency[key]
     return dependency
 
+def is_star(val):
+    return isinstance(val, six.string_types) and val == '*'
+
+def is_pinned(val):
+    return isinstance(val, six.string_types) and val.startswith('==')
 
 def convert_deps_to_pip(deps, project=None, r=True, include_index=False):
     """"Converts a Pipfile-formatted dependency to a pip-formatted one."""
 
     dependencies = []
 
-    def is_star(val):
-        return isinstance(val, six.string_types) and val == '*'
-
     for dep in deps.keys():
 
         # Default (e.g. '>1.10').