diff --git a/aider/coders/base_coder.py b/aider/coders/base_coder.py
index 6d5da2eb1..780c51595 100755
--- a/aider/coders/base_coder.py
+++ b/aider/coders/base_coder.py
@@ -775,7 +775,7 @@ class Coder:
                 f"- The user's language: {user_lang}\n"
             )
 
-        dt = datetime.now().isoformat()
+        dt = datetime.now().strftime("%Y-%m-%dT%H:%M:%S")
         platform_text += f"- The current date/time: {dt}"
 
         prompt = prompt.format(