diff --git a/src/toOpenAIMessages.ts b/src/toOpenAIMessages.ts
index b0f2ea9..b1a432d 100644
--- a/src/toOpenAIMessages.ts
+++ b/src/toOpenAIMessages.ts
@@ -72,8 +72,8 @@ function formatName(name: string): string {
     .replace(/[^a-zA-Z0-9_-]/g, "_")
     // remove trailing '-_' characters
     .replace(/^[-_]+|[-_]+$/g, "")
-    // remove duplicated '-_' characters
-    .replace(/([-_])*/g, "$1");
+    // remove duplicated '-_' character sequences
+    .replace(/([-_])([-_])+/g, "$1");
 }
 
 /**