diff --git a/include/gp/algorithm/tmp_manip.hpp b/include/gp/algorithm/tmp_manip.hpp
index 80af38f..058c8e8 100644
--- a/include/gp/algorithm/tmp_manip.hpp
+++ b/include/gp/algorithm/tmp_manip.hpp
@@ -202,7 +202,7 @@ namespace gp{
 		typedef std::true_type yes;
 		typedef std::false_type no;
 	
-		template<typename U, void* (U::*f)(size_t) const> struct SFINAE{};
+		template<typename U, void* (U::*f)(size_t)> struct SFINAE{};
 	
 	
 		template<class C> static yes test(SFINAE<C,&C::allocate>*);
@@ -219,7 +219,7 @@ namespace gp{
 		typedef std::true_type yes;
 		typedef std::false_type no;
 	
-		template<typename U, void (U::*f)(void*) const> struct SFINAE{};
+		template<typename U, bool (U::*f)(void*)> struct SFINAE{};
 	
 	
 		template<class C> static yes test(SFINAE<C,&C::deallocate>*);
diff --git a/include/gp/allocator/arena.hpp b/include/gp/allocator/arena.hpp
index 6fd38cf..118a2bd 100644
--- a/include/gp/allocator/arena.hpp
+++ b/include/gp/allocator/arena.hpp
@@ -7,7 +7,7 @@
 
 
 namespace gp{
-	template<typename page_allocator, size_t align = 1>
+	template<typename page_allocator = int, size_t align = 1>
 	class arena{
 		page_allocator allocator;
 		gp::buffer<char> data;
@@ -20,18 +20,20 @@ namespace gp{
 		,data(gp::buffer<char>(nullptr,nullptr))
 		{}
 
-		template<typename T = typename std::enable_if<gp::has_allocator_interface<page_allocator>::value,int>::type>
 		arena(size_t sz)
 		:last(0)
 		,count(0)
 		,data(nullptr,nullptr)
 		{
-			if(sz!=0)
+			if constexpr (gp::has_allocator_interface<page_allocator>::value)
 			{
-				auto v=allocator.allocate(sz);
-				if(v!=nullptr)
+				if(sz!=0)
 				{
-					data=gp::buffer<char>(reinterpret_cast<char*>(v),reinterpret_cast<char*>(v)+sz);
+					auto v=allocator.allocate(sz);
+					if(v!=nullptr)
+					{
+						data=gp::buffer<char>(reinterpret_cast<char*>(v),reinterpret_cast<char*>(v)+sz);
+					}
 				}
 			}
 		}
diff --git a/include/gp/ring_list.hpp b/include/gp/ring_list.hpp
index 37a98e8..62b24b6 100644
--- a/include/gp/ring_list.hpp
+++ b/include/gp/ring_list.hpp
@@ -95,13 +95,22 @@ namespace gp {
 		, alloc{_alloc}
 		{}
 
+		ring_list(allocator& _alloc)
+		: any_node{nullptr}
+		, sz{0}
+		, alloc{_alloc}
+		{}
+
 		template<typename V = T, typename ...Args>
 		bool insert(Args&&... elem) {
 			allocator& used_allocator = alloc;
-			void* mem = used_allocator.allocate(sizeof(V));
+			void* mem;
+			[[unlikely]] if(
+				nullptr == (mem = used_allocator.allocate(sizeof(V)))
+			) return false;
 			T* p = new(mem) V(elem...);
 			node* to_insert = nullptr;
-			if(
+			[[unlikely]] if(
 				nullptr == (to_insert = reinterpret_cast<node*>(used_allocator.allocate(sizeof(node))))
 			) return false;
 			to_insert = new(to_insert) node(p);
diff --git a/tests/gp_test.cpp b/tests/gp_test.cpp
index 8b15735..c52824f 100644
--- a/tests/gp_test.cpp
+++ b/tests/gp_test.cpp
@@ -3,6 +3,7 @@
 #include "gp/array.hpp"
 #include "gp/indexed_array.hpp"
 #include "gp/allocator/aggregator.hpp"
+#include "gp/allocator/arena.hpp"
 #include "gp/allocator/buddy.hpp"
 #include "gp/allocator/dummy.hpp"
 #include "gp/algorithm/repeat.hpp"
@@ -414,6 +415,35 @@ struct aggregator_test : public test_scaffold {
 			}
 			auto duration = std::chrono::steady_clock::now() - start;
 		}
+		void* a = allocator.allocate(8);
+		gp_config::assertion(allocator.try_reallocate(a, 16) == false, "could reallocate? was it implemented?");
+		gp_config::assertion(allocator.deallocate(nullptr) == false, "error, could free an invalid pointer");
+		allocator.deallocate(a);
+		{
+			gp::ring_list<int, gp::aggregator, false> list{allocator};
+			list.insert(8);
+			list.insert(16);
+			list.insert(32);
+		}
+		{
+			gp::array<char, 256> work_array;
+			gp::arena<> alloc_work(work_array.begin().data, work_array.size());
+			gp::ring_list<int, gp::arena<>, false> list{alloc_work};
+			gp_config::assertion(list.insert(8) == true, "could allocate in list with good enough allocator");
+			gp_config::assertion(list.insert(8) == true, "could allocate in list with good enough allocator");
+			gp_config::assertion(list.insert(8) == true, "could allocate in list with good enough allocator");
+		}
+		{
+			gp::array<char, sizeof(int)> once_array;
+			gp::arena<> alloc_once(once_array.begin().data, once_array.size());
+			gp::ring_list<int, gp::arena<>, false> list{alloc_once};
+			gp_config::assertion(list.insert(8) == false, "could allocate in list with insufficient allocator");
+		}
+		{
+			gp::arena<> alloc_none(nullptr, 0);
+			gp::ring_list<int, gp::arena<>, false> list{alloc_none};
+			gp_config::assertion(list.insert(8) == false, "could allocate in list with fake allocator");
+		}
 		return res;
 	}
 };