diff --git a/aider/coder.py b/aider/coder.py
index 90e035039..b9db304c2 100755
--- a/aider/coder.py
+++ b/aider/coder.py
@@ -10,6 +10,7 @@ from rich.console import Console
 from rich.live import Live
 from rich.markdown import Markdown
 from pathlib import Path
+import tiktoken
 
 import git
 import openai
@@ -74,6 +75,7 @@ class Coder:
 
         self.pretty = pretty
         self.show_diffs = show_diffs
+        self.tokenizer = tiktoken.encoding_for_model(self.main_model)
 
     def find_common_root(self):
         if self.abs_fnames:
@@ -169,37 +171,25 @@ class Coder:
             files_content += self.get_files_content()
             all_content += files_content
 
-        if self.repo is not None:
-            other_files = set(self.get_all_abs_files()) - set(self.abs_fnames)
-            if other_files:
-                if self.use_ctags:
-                    files_listing = get_tags_map(other_files)
-                    ctags_msg = " with selected ctags info"
-                else:
-                    files_listing = "\n".join(
-                        self.get_rel_fname(ofn) for ofn in sorted(other_files)
-                    )
-                    ctags_msg = ""
+        res = self.choose_files_listing()
+        if res:
+            files_listing, ctags_msg = res
 
-                if self.abs_fnames:
-                    other = "other "
-                else:
-                    other = ""
+            if self.abs_fnames:
+                other = "other "
+            else:
+                other = ""
 
-                repo_content = prompts.repo_content_prefix.format(
-                    other=other,
-                    ctags_msg=ctags_msg,
-                )
-                repo_content += files_listing
+            repo_content = prompts.repo_content_prefix.format(
+                other=other,
+                ctags_msg=ctags_msg,
+            )
+            repo_content += files_listing
 
-                from .dump import dump
+            if all_content:
+                all_content += "\n\n"
 
-                dump(len(repo_content))
-
-                if all_content:
-                    all_content += "\n\n"
-
-                all_content += repo_content
+            all_content += repo_content
 
         files_messages = [
             dict(role="user", content=all_content),
@@ -212,6 +202,35 @@ class Coder:
 
         return files_messages
 
+    def choose_files_listing(self):
+        # 1/4 of gpt-4's context window
+        max_map_tokens = 2048
+
+        if not self.repo:
+            return
+
+        other_files = set(self.get_all_abs_files()) - set(self.abs_fnames)
+        if not other_files:
+            return
+
+        if self.use_ctags:
+            files_listing = get_tags_map(other_files)
+            if self.token_count(files_listing) < max_map_tokens:
+                ctags_msg = " with selected ctags info"
+                return files_listing, ctags_msg
+
+        files_listing = self.get_simple_files_map(other_files)
+        ctags_msg = ""
+        if self.token_count(files_listing) < max_map_tokens:
+            return files_listing, ctags_msg
+
+    def get_simple_files_map(self, other_files):
+        files_listing = "\n".join(self.get_rel_fname(ofn) for ofn in sorted(other_files))
+        return files_listing
+
+    def token_count(self, string):
+        return len(self.tokenizer.encode(string))
+
     def run(self):
         self.done_messages = []
         self.cur_messages = []
diff --git a/requirements.txt b/requirements.txt
index 47a9a6e08..38a272b95 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -23,3 +23,4 @@ urllib3==2.0.2
 wcwidth==0.2.6
 yarl==1.9.2
 pytest==7.3.1
+tiktoken==0.4.0