diff --git a/src/resources/extensions/sf/auto-model-selection.ts b/src/resources/extensions/sf/auto-model-selection.ts
index 281e4b7e5..ce978a736 100644
--- a/src/resources/extensions/sf/auto-model-selection.ts
+++ b/src/resources/extensions/sf/auto-model-selection.ts
@@ -707,7 +707,7 @@ export function buildFlatRateContext(
   prefs?: { flat_rate_providers?: readonly string[] },
 ): FlatRateContext {
   let authMode: FlatRateContext["authMode"];
-  const getAuthMode = ctx?.modelRegistry?.getProviderAuthMode;
+  const getAuthMode = ctx?.modelRegistry?.getProviderAuthMode?.bind(ctx.modelRegistry);
   if (typeof getAuthMode === "function") {
     try {
       const mode = getAuthMode(provider);