diff --git a/src/providers/gemini.rs b/src/providers/gemini.rs
index d7628865..e59d14b5 100644
--- a/src/providers/gemini.rs
+++ b/src/providers/gemini.rs
@@ -57,7 +57,7 @@ struct GeminiPart {
     function_response: Option<GeminiFunctionResponse>,
     #[serde(skip_serializing_if = "Option::is_none")]
     thought: Option<String>,
-    #[serde(skip_serializing_if = "Option::is_none", rename = "thoughtSignature")]
+    #[serde(skip_serializing_if = "Option::is_none", rename = "thought_signature")]
     thought_signature: Option<String>,
 }