diff --git a/pipreqs/pipreqs.py b/pipreqs/pipreqs.py
index dceda96..1887e9c 100644
--- a/pipreqs/pipreqs.py
+++ b/pipreqs/pipreqs.py
@@ -164,6 +164,7 @@ def get_all_imports(path, encoding="utf-8", extra_ignore_dirs=None, follow_links
         imports.add(cleaned_name)
 
     packages = imports - (set(candidates) & imports)
+    packages = {p.lower() for p in packages}
     logging.debug("Found packages: {0}".format(packages))
 
     with open(join("stdlib"), "r") as f:
@@ -283,7 +284,7 @@ def get_locally_installed_packages(encoding="utf-8"):
                         for module in top_level_modules:
                             if (module not in ignore) and (package[0] not in ignore):
                                 # append exported top level modules to the list
-                                filtered_top_level_modules.append(module)
+                                filtered_top_level_modules.append(module.lower())
 
                         version = None
                         if len(package) > 1:
@@ -293,7 +294,7 @@ def get_locally_installed_packages(encoding="utf-8"):
                         # instead of top_level_module: package pairs
                         packages.append(
                             {
-                                "name": package[0],
+                                "name": package[0].lower(),
                                 "version": version,
                                 "exports": filtered_top_level_modules,
                             }
@@ -338,7 +339,7 @@ def get_pkg_names(pkgs):
     for pkg in pkgs:
         # Look up the mapped requirement. If a mapping isn't found,
         # simply use the package name.
-        result.add(data.get(pkg, pkg))
+        result.add(data.get(pkg, pkg).lower())
     # Return a sorted list for backward compatibility.
     return sorted(result, key=lambda s: s.lower())