diff --git a/runtime/dex_file.h b/runtime/dex_file.h
index 29b8c3a..07daf81 100644
--- a/runtime/dex_file.h
+++ b/runtime/dex_file.h
@@ -639,6 +639,9 @@
   // Returns a representation of the signature of a method id.
   const Signature GetMethodSignature(const MethodId& method_id) const;
 
+  // Returns a representation of the signature of a proto id.
+  const Signature GetProtoSignature(const ProtoId& proto_id) const;
+
   // Returns the name of a method id.
   const char* GetMethodName(const MethodId& method_id) const;