diff --git a/packages/core/lib/modelUtils.ts b/packages/core/lib/modelUtils.ts
index db6b968f8..565590d0e 100644
--- a/packages/core/lib/modelUtils.ts
+++ b/packages/core/lib/modelUtils.ts
@@ -17,6 +17,9 @@ export function splitModelName(model: string): {
   modelName: string;
 } {
   const firstSlashIndex = model.indexOf("/");
+  if (firstSlashIndex === -1) {
+    return { provider: "", modelName: model };
+  }
   const provider = model.substring(0, firstSlashIndex);
   const modelName = model.substring(firstSlashIndex + 1);
   return { provider, modelName };