diff --git a/keystore/KeyStore.h b/keystore/KeyStore.h
index 25ff3a5..69a02ae 100644
--- a/keystore/KeyStore.h
+++ b/keystore/KeyStore.h
@@ -62,7 +62,7 @@
 }  // namespace keystore
 
 namespace std {
-template <typename T, size_t count> class tuple_size<keystore::Devices<T, count>> {
+template <typename T, size_t count> struct tuple_size<keystore::Devices<T, count>> {
   public:
     static constexpr size_t value = std::tuple_size<std::array<T, count>>::value;
 };