diff --git a/aider/commands.py b/aider/commands.py
index a0aacedbd..559690011 100644
--- a/aider/commands.py
+++ b/aider/commands.py
@@ -272,13 +272,12 @@ class Commands:
         git_files = self.coder.repo.get_tracked_files() if self.coder.repo else []
 
         all_matched_files = set()
-        for word in args.split():
+        for word in shlex.split(args):
             fname = Path(self.coder.root) / word
-            if fname.exists():
-                if fname.is_file():
-                    all_matched_files.add(str(fname))
-                    continue
-                # else we fall through and glob will pickup all files within a dir
+            if fname.exists() and fname.is_file():
+                all_matched_files.add(str(fname))
+                continue
+                # an existing dir will fall through and get recursed by glob
 
             matched_files = self.glob_filtered_to_repo(word)
             if matched_files:
@@ -342,7 +341,7 @@ class Commands:
             self.io.tool_output("Dropping all files from the chat session.")
             self.coder.abs_fnames = set()
 
-        for word in args.split():
+        for word in shlex.split(args):
             matched_files = self.glob_filtered_to_repo(word)
 
             if not matched_files:
diff --git a/tests/test_commands.py b/tests/test_commands.py
index 29976a77b..89524e73b 100644
--- a/tests/test_commands.py
+++ b/tests/test_commands.py
@@ -372,3 +372,33 @@ class TestCommands(TestCase):
             commands.cmd_add(str(fname))
 
             self.assertIn(str(fname.resolve()), coder.abs_fnames)
+
+    def test_cmd_add_abs_filename(self):
+        with ChdirTemporaryDirectory():
+            io = InputOutput(pretty=False, yes=False)
+            from aider.coders import Coder
+
+            coder = Coder.create(models.GPT35, None, io)
+            commands = Commands(io, coder)
+
+            fname = Path("file.txt")
+            fname.touch()
+
+            commands.cmd_add(str(fname.resolve()))
+
+            self.assertIn(str(fname.resolve()), coder.abs_fnames)
+
+    def test_cmd_add_quoted_filename(self):
+        with ChdirTemporaryDirectory():
+            io = InputOutput(pretty=False, yes=False)
+            from aider.coders import Coder
+
+            coder = Coder.create(models.GPT35, None, io)
+            commands = Commands(io, coder)
+
+            fname = Path("file with spaces.txt")
+            fname.touch()
+
+            commands.cmd_add(f'"{fname}"')
+
+            self.assertIn(str(fname.resolve()), coder.abs_fnames)