diff --git a/aider/args.py b/aider/args.py
index b880605a90a..e565bc4438e 100644
--- a/aider/args.py
+++ b/aider/args.py
@@ -303,6 +303,15 @@ def get_parser(default_config_files, git_root):
         type=float,
         default=2,
         help="Multiplier for map tokens when no files are specified (default: 2)",
+    ) 
+    group.add_argument(
+        "--map-cache-dir",
+        metavar="MAP_CACHE_DIR",
+        default=".",
+        help=(
+            "Root directory for the repository map cache .aider.tags.cache.v3"
+            " (default: current directory)"
+        ),
     )
 
     ##########
diff --git a/aider/coders/base_coder.py b/aider/coders/base_coder.py
index 8e781437227..89de89e35a0 100755
--- a/aider/coders/base_coder.py
+++ b/aider/coders/base_coder.py
@@ -295,7 +295,11 @@ def __init__(
         ignore_mentions=None,
         file_watcher=None,
         auto_copy_context=False,
+        map_root='.',
     ):
+        # initialize from args.map_root
+        self.map_root = map_root
+        
         # Fill in a dummy Analytics if needed, but it is never .enable()'d
         self.analytics = analytics if analytics is not None else Analytics()
 
@@ -442,7 +446,7 @@ def __init__(
         if use_repo_map and self.repo and has_map_prompt:
             self.repo_map = RepoMap(
                 map_tokens,
-                self.root,
+                self.map_root,
                 self.main_model,
                 io,
                 self.gpt_prompts.repo_content_prefix,
diff --git a/aider/main.py b/aider/main.py
index 943c74d21dc..243a492d5e0 100644
--- a/aider/main.py
+++ b/aider/main.py
@@ -886,6 +886,7 @@ def get_io(pretty):
             chat_language=args.chat_language,
             detect_urls=args.detect_urls,
             auto_copy_context=args.copy_paste,
+            map_root=args.map_root, # initialize from args.map_root
         )
     except UnknownEditFormat as err:
         io.tool_error(str(err))
diff --git a/aider/repomap.py b/aider/repomap.py
index 23f40ba71f9..bd30a92132c 100644
--- a/aider/repomap.py
+++ b/aider/repomap.py
@@ -78,6 +78,9 @@ def __init__(
             self.io.tool_output(
                 f"RepoMap initialized with map_mul_no_files: {self.map_mul_no_files}"
             )
+            self.io.tool_output(
+                f"RepoMap initialized with map_root: {self.root}"
+            )
 
     def token_count(self, text):
         len_text = len(text)