diff --git a/Keymaster.h b/Keymaster.h
index 003baa6..a4deddf 100644
--- a/Keymaster.h
+++ b/Keymaster.h
@@ -33,7 +33,6 @@
 // This is tailored to the needs of KeyStorage, but could be extended to be
 // a more general interface.
 
-
 // Wrapper for a keymaster_operation_handle_t representing an
 // ongoing Keymaster operation.  Aborts the operation
 // in the destructor if it is unfinished. Methods log failures
@@ -100,6 +99,12 @@
     return params.Authorization(tag, val.data(), val.size());
 }
 
+template <keymaster_tag_t Tag>
+inline void addStringParam(AuthorizationSetBuilder &params,
+        TypedTag<KM_BYTES, Tag> tag, const std::string& val) {
+    params.Authorization(tag, val.data(), val.size());
+}
+
 }  // namespace vold
 }  // namespace android