diff --git a/news/3745.bugfix.rst b/news/3745.bugfix.rst
new file mode 100644
index 0000000000..229047a40d
--- /dev/null
+++ b/news/3745.bugfix.rst
@@ -0,0 +1 @@
+Normalize the package names to lowercase when comparing used and in-Pipfile packages.
diff --git a/pipenv/core.py b/pipenv/core.py
index 65541857f2..7f04ac4999 100644
--- a/pipenv/core.py
+++ b/pipenv/core.py
@@ -242,7 +242,9 @@ def import_from_code(path="."):
 
     rs = []
     try:
-        for r in pipreqs.get_all_imports(path):
+        for r in pipreqs.get_all_imports(
+            path, encoding="utf-8", extra_ignore_dirs=[".venv"]
+        ):
             if r not in BAD_PACKAGES:
                 rs.append(r)
         pkg_names = pipreqs.get_pkg_names(rs)
@@ -2537,8 +2539,8 @@ def do_check(
     if not args:
         args = []
     if unused:
-        deps_required = [k for k in project.packages.keys()]
-        deps_needed = import_from_code(unused)
+        deps_required = [k.lower() for k in project.packages.keys()]
+        deps_needed = [k.lower() for k in import_from_code(unused)]
         for dep in deps_needed:
             try:
                 deps_required.remove(dep)
diff --git a/tests/integration/test_cli.py b/tests/integration/test_cli.py
index 82b17e17ed..f131ae4440 100644
--- a/tests/integration/test_cli.py
+++ b/tests/integration/test_cli.py
@@ -217,20 +217,20 @@ def test_install_parse_error(PipenvInstance, pypi):
 @pytest.mark.code
 @pytest.mark.check
 @pytest.mark.unused
-@pytest.mark.skip(reason="non-deterministic")
+@pytest.mark.needs_internet(reason='required by check')
 def test_check_unused(PipenvInstance, pypi):
     with PipenvInstance(chdir=True, pypi=pypi) as p:
         with open('__init__.py', 'w') as f:
             contents = """
 import tablib
 import records
+import flask
             """.strip()
             f.write(contents)
-        p.pipenv('install requests')
-        p.pipenv('install tablib')
-        p.pipenv('install records')
+        p.pipenv('install requests tablib flask')
 
-        assert all(pkg in p.pipfile['packages'] for pkg in ['requests', 'tablib', 'records'])
+        assert all(pkg in p.pipfile['packages'] for pkg in ['requests', 'tablib', 'flask'])
 
         c = p.pipenv('check --unused .')
         assert 'tablib' not in c.out
+        assert 'flask' not in c.out