diff --git a/CMakeLists.txt b/CMakeLists.txt
index 88716a7..840d6fc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.20)
 include(cmake/color.cmake)
-set(BLT_VERSION 0.18.39)
+set(BLT_VERSION 0.18.40)
 set(BLT_TEST_VERSION 0.0.1)
 
 set(BLT_TARGET BLT)
diff --git a/include/blt/std/meta.h b/include/blt/std/meta.h
index 56203fb..57cd624 100644
--- a/include/blt/std/meta.h
+++ b/include/blt/std/meta.h
@@ -26,7 +26,7 @@
 
 namespace blt::meta
 {
-    template<typename IFirst, typename... IArgs>
+    template<typename IFirst = std::void_t<void>, typename... IArgs>
     struct arg_helper
     {
         using First = IFirst;
@@ -41,7 +41,7 @@ namespace blt::meta
     };
     
     template<>
-    struct arg_helper<void>
+    struct arg_helper<>
     {
         using First = void;
         using Next = void;
diff --git a/libraries/parallel-hashmap b/libraries/parallel-hashmap
index d88c5e1..8a889d3 160000
--- a/libraries/parallel-hashmap
+++ b/libraries/parallel-hashmap
@@ -1 +1 @@
-Subproject commit d88c5e15079047777b418132ece5879e7c9aaa2b
+Subproject commit 8a889d3699b3c09ade435641fb034427f3fd12b6