diff --git a/pipenv/core.py b/pipenv/core.py
index 4346f487..7b30af90 100644
--- a/pipenv/core.py
+++ b/pipenv/core.py
@@ -2127,8 +2127,7 @@ def do_uninstall(
                 bold=True,
             )
         )
-        package_names = project.parsed_pipfile['dev-packages']
-        package_names = package_names.keys()
+        package_names = project.dev_packages.keys()
     if package_name is False and not all_dev:
         click.echo(crayons.red('No package provided!'), err=True)
         sys.exit(1)
diff --git a/pipenv/patched/prettytoml/elements/abstracttable.py b/pipenv/patched/prettytoml/elements/abstracttable.py
index 48663aed..6a2c174a 100644
--- a/pipenv/patched/prettytoml/elements/abstracttable.py
+++ b/pipenv/patched/prettytoml/elements/abstracttable.py
@@ -24,7 +24,10 @@ class AbstractTable(ContainerElement, traversal.TraversalMixin, Mapping):
         """
         non_metadata = self._enumerate_non_metadata_sub_elements()
         while True:
-            yield next(non_metadata), next(non_metadata)
+            try:
+                yield next(non_metadata), next(non_metadata)
+            except StopIteration:
+                return
 
     def items(self):
         for (key_i, key), (value_i, value) in self._enumerate_items():
diff --git a/pipenv/project.py b/pipenv/project.py
index 0a9e04be..db515acf 100644
--- a/pipenv/project.py
+++ b/pipenv/project.py
@@ -624,7 +624,7 @@ class Project(object):
             formatted_data = contoml.dumps(data).rstrip()
         except Exception:
             for section in ('packages', 'dev-packages'):
-                for package in data[section]:
+                for package in data.get(section, {}):
                     # Convert things to inline tables — fancy :)
                     if hasattr(data[section][package], 'keys'):
                         _data = data[section][package]
diff --git a/tests/integration/test_install_markers.py b/tests/integration/test_install_markers.py
index 0b885493..ca6b70fe 100644
--- a/tests/integration/test_install_markers.py
+++ b/tests/integration/test_install_markers.py
@@ -11,6 +11,7 @@ from flaky import flaky
 
 
 py3_only = pytest.mark.skipif(sys.version_info < (3, 0), reason="requires Python3")
+skip_py37 = pytest.mark.skipif(sys.version_info >= (3, 7), reason="Skip for python 3.7")
 
 
 @pytest.mark.markers
@@ -127,6 +128,7 @@ funcsigs = "*"
 @pytest.mark.complex
 @flaky
 @py3_only
+@skip_py37
 def test_resolver_unique_markers(PipenvInstance, pypi):
     """vcrpy has a dependency on `yarl` which comes with a marker
     of 'python version in "3.4, 3.5, 3.6" - this marker duplicates itself: