diff --git a/include/etl/generators/type_traits_generator.h b/include/etl/generators/type_traits_generator.h
index 9e6bfc8a..1babf113 100644
--- a/include/etl/generators/type_traits_generator.h
+++ b/include/etl/generators/type_traits_generator.h
@@ -584,7 +584,7 @@ namespace etl
   template <typename T, unsigned MAXN>
   struct extent<T[MAXN], 0> : integral_constant<size_t, MAXN> {};
 
-  template <typename T, size_t I, unsigned MAXN>
+  template <typename T, unsigned I, unsigned MAXN>
   struct extent<T[I], MAXN> : integral_constant<size_t, extent<T, MAXN - 1>::value> {};
 
 #if ETL_CPP17_SUPPORTED
diff --git a/include/etl/type_traits.h b/include/etl/type_traits.h
index 9dacb455..c667e9b7 100644
--- a/include/etl/type_traits.h
+++ b/include/etl/type_traits.h
@@ -572,7 +572,7 @@ namespace etl
   template <typename T, unsigned MAXN>
   struct extent<T[MAXN], 0> : integral_constant<size_t, MAXN> {};
 
-  template <typename T, size_t I, unsigned MAXN>
+  template <typename T, unsigned I, unsigned MAXN>
   struct extent<T[I], MAXN> : integral_constant<size_t, extent<T, MAXN - 1>::value> {};
 
 #if ETL_CPP17_SUPPORTED