diff --git a/aider/main.py b/aider/main.py
index efc575818..91b4807a1 100644
--- a/aider/main.py
+++ b/aider/main.py
@@ -759,7 +759,6 @@ def main(argv=None, input=None, output=None, force_git_root=None, return_coder=F
             ("OPENROUTER_API_KEY", "openrouter/anthropic/claude-3.7-sonnet"),
             ("OPENAI_API_KEY", "gpt-4o"),
             ("GEMINI_API_KEY", "gemini/gemini-2.5-pro-exp-03-25"),
-            ("VERTEX_AI_API_KEY", "gemini/gemini-2.5-pro-exp-03-25"),
             ("VERTEXAI_PROJECT", "vertex_ai/gemini-2.5-pro-exp-03-25"),
         ]