diff --git a/django/core/files/storage.py b/django/core/files/storage.py
index 4c27fce6052..e9166d94ff0 100644
--- a/django/core/files/storage.py
+++ b/django/core/files/storage.py
@@ -291,7 +291,7 @@ class FileSystemStorage(Storage):
             os.chmod(full_path, self.file_permissions_mode)
 
         # Store filenames with forward slashes, even on Windows.
-        return name.replace('\\', '/')
+        return str(name).replace('\\', '/')
 
     def delete(self, name):
         assert name, "The name argument is not allowed to be empty."
diff --git a/docs/ref/files/storage.txt b/docs/ref/files/storage.txt
index b2710062df1..542eb2dc7ed 100644
--- a/docs/ref/files/storage.txt
+++ b/docs/ref/files/storage.txt
@@ -69,6 +69,11 @@ The ``FileSystemStorage`` class
         time of the last metadata change, and on others (like Windows), it's
         the creation time of the file.
 
+.. versionchanged:: 3.1
+
+    Support for :class:`pathlib.Path` was added to the
+    ``FileSystemStorage.save()`` method.
+
 The ``Storage`` class
 =====================
 
diff --git a/docs/releases/3.1.txt b/docs/releases/3.1.txt
index d928abd2057..ef2ab9b1733 100644
--- a/docs/releases/3.1.txt
+++ b/docs/releases/3.1.txt
@@ -124,7 +124,7 @@ Email
 File Storage
 ~~~~~~~~~~~~
 
-* ...
+* ``FileSystemStorage.save()`` method now supports :class:`pathlib.Path`.
 
 File Uploads
 ~~~~~~~~~~~~
diff --git a/tests/file_storage/tests.py b/tests/file_storage/tests.py
index 779116b3bd2..be6e11de93c 100644
--- a/tests/file_storage/tests.py
+++ b/tests/file_storage/tests.py
@@ -545,7 +545,7 @@ class FileStorageTests(SimpleTestCase):
         p = Path('test.file')
         self.assertFalse(self.storage.exists(p))
         f = ContentFile('custom contents')
-        f_name = self.storage.save(str(p), f)
+        f_name = self.storage.save(p, f)
         # Storage basic methods.
         self.assertEqual(self.storage.path(p), os.path.join(self.temp_dir, p))
         self.assertEqual(self.storage.size(p), 15)
@@ -560,10 +560,10 @@ class CustomStorage(FileSystemStorage):
         """
         Append numbers to duplicate files rather than underscores, like Trac.
         """
-        basename, *ext = name.split('.')
+        basename, *ext = os.path.splitext(name)
         number = 2
         while self.exists(name):
-            name = '.'.join([basename, str(number)] + ext)
+            name = ''.join([basename, '.', str(number)] + ext)
             number += 1
 
         return name