diff --git a/dspy/clients/lm.py b/dspy/clients/lm.py
index 0198591302..abc97a845b 100644
--- a/dspy/clients/lm.py
+++ b/dspy/clients/lm.py
@@ -79,7 +79,7 @@ def __init__(
         model_family = model.split("/")[-1].lower() if "/" in model else model.lower()
 
         # Match pattern: o[1,3,4] at the start, optionally followed by -mini and anything else
-        model_pattern = re.match(r"^o([134])(?:-mini)?", model_family)
+        model_pattern = re.match(r"^(?:o([1345])|gpt-(5))(?:-mini)?", model_family)
 
         if model_pattern:
             # Handle OpenAI reasoning models (o1, o3)