diff --git a/aider/coder.py b/aider/coder.py
index 97fe0fcf5..4adcf94e8 100755
--- a/aider/coder.py
+++ b/aider/coder.py
@@ -72,13 +72,14 @@ class Coder:
         else:
             self.console = Console(force_terminal=True, no_color=True)
 
+        main_model = Models(main_model)
         if not self.check_model_availability(main_model):
-            main_model = Models.GPT35.value
+            main_model = Models.GPT35
 
         self.main_model = main_model
-        if main_model == Models.GPT35.value:
+        if main_model == Models.GPT35:
             self.io.tool_output(
-                f"Using {main_model}: showing diffs and disabling ctags/repo-maps.",
+                f"Using {main_model.value}: showing diffs and disabling ctags/repo-maps.",
             )
             self.gpt_prompts = prompts.GPT35()
             map_tokens = 0
@@ -108,7 +109,7 @@ class Coder:
             self.gpt_prompts.repo_content_prefix,
         )
 
-        if main_model != Models.GPT35.value:
+        if main_model != Models.GPT35:
             if self.repo_map.has_ctags:
                 self.io.tool_output("Using ctags to build repo-map.")
 
@@ -301,7 +302,7 @@ class Coder:
         ]
 
         main_sys = self.gpt_prompts.main_system
-        if self.main_model == Models.GPT4.value:
+        if self.main_model == Models.GPT4:
             main_sys += "\n" + self.gpt_prompts.system_reminder
 
         messages = [
@@ -328,7 +329,7 @@ class Coder:
         if edit_error:
             return edit_error
 
-        if self.main_model == "gpt=4" or (self.main_model == Models.GPT35.value and not edited):
+        if self.main_model == Models.GPT4 or (self.main_model == Models.GPT35 and not edited):
             # Don't add assistant messages to the history if they contain "edits"
             # Because those edits are actually fully copies of the file!
             # That wastes too much context window.
@@ -422,7 +423,7 @@ class Coder:
 
     def send(self, messages, model=None, silent=False):
         if not model:
-            model = self.main_model
+            model = self.main_model.value
 
         self.resp = ""
         interrupted = False
@@ -720,12 +721,12 @@ class Coder:
         return set(self.get_all_relative_files()) - set(self.get_inchat_relative_files())
 
     def apply_updates(self, content):
-        if self.main_model == Models.GPT4.value:
+        if self.main_model == Models.GPT4:
             method = self.update_files_gpt4
-        elif self.main_model == Models.GPT35.value:
+        elif self.main_model == Models.GPT35:
             method = self.update_files_gpt35
         else:
-            raise ValueError(f"apply_updates() doesn't support {self.main_model}")
+            raise ValueError(f"apply_updates() doesn't support {self.main_model.value}")
 
         try:
             edited = method(content)
diff --git a/aider/commands.py b/aider/commands.py
index 47599a289..a83e58dee 100644
--- a/aider/commands.py
+++ b/aider/commands.py
@@ -16,7 +16,7 @@ class Commands:
     def __init__(self, io, coder):
         self.io = io
         self.coder = coder
-        self.tokenizer = tiktoken.encoding_for_model(coder.main_model)
+        self.tokenizer = tiktoken.encoding_for_model(coder.main_model.value)
 
     def is_command(self, inp):
         if inp[0] == "/":
@@ -133,7 +133,7 @@ class Commands:
         print()
         print(f"{total:6.3f} total")
 
-        limit = 8 if self.coder.main_model == Models.GPT4.value else 4
+        limit = 8 if self.coder.main_model == Models.GPT4 else 4
         remaining = limit - total
         print(f"{remaining:6.3f} remaining")
         print(f"{limit:6.3f} max context window")
@@ -181,7 +181,7 @@ class Commands:
             "was reset and removed from git.\n"
         )
 
-        if self.coder.main_model != Models.GPT35.value:
+        if self.coder.main_model != Models.GPT35:
             return prompts.undo_command_reply
 
     def cmd_diff(self, args):
diff --git a/aider/repomap.py b/aider/repomap.py
index 5d9c54d05..87d984c5b 100644
--- a/aider/repomap.py
+++ b/aider/repomap.py
@@ -69,7 +69,7 @@ class RepoMap:
         self,
         map_tokens=1024,
         root=None,
-        main_model=Models.GPT4.value,
+        main_model=Models.GPT4,
         io=None,
         repo_content_prefix=None,
     ):
@@ -88,7 +88,7 @@ class RepoMap:
         else:
             self.has_ctags = False
 
-        self.tokenizer = tiktoken.encoding_for_model(main_model)
+        self.tokenizer = tiktoken.encoding_for_model(main_model.value)
         self.repo_content_prefix = repo_content_prefix
 
     def get_repo_map(self, chat_files, other_files):