diff --git a/aider/coders/base_coder.py b/aider/coders/base_coder.py
index 1e5d6849a..9b7a1d2a4 100755
--- a/aider/coders/base_coder.py
+++ b/aider/coders/base_coder.py
@@ -706,7 +706,8 @@ class Coder:
             tokens = f"{prompt_tokens} prompt tokens, {completion_tokens} completion tokens"
             if self.main_model.prompt_price:
                 cost = prompt_tokens * self.main_model.prompt_price / 1000
-                cost += completion_tokens * self.main_model.completion_price / 1000
+                if self.main_model.completion_price:
+                    cost += completion_tokens * self.main_model.completion_price / 1000
                 tokens += f", ${cost:.6f} cost"
                 self.total_cost += cost
 
diff --git a/aider/models/openai.py b/aider/models/openai.py
index 2a134fee8..81e3d6af5 100644
--- a/aider/models/openai.py
+++ b/aider/models/openai.py
@@ -12,7 +12,7 @@ class ModelInfo:
     name: str
     max_context_tokens: int
     prompt_price: float
-    completions_price: float
+    completion_price: float
     edit_format: str
     always_available: bool = False
     use_repo_map: bool = False