diff --git a/CMakeLists.txt b/CMakeLists.txt
index bed19f6..4daa5b6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.20)
 include(cmake/color.cmake)
-set(BLT_VERSION 0.18.19)
+set(BLT_VERSION 0.18.20)
 set(BLT_TEST_VERSION 0.0.1)
 
 set(BLT_TARGET BLT)
diff --git a/include/blt/std/utility.h b/include/blt/std/utility.h
index 2be3245..cf6ab87 100644
--- a/include/blt/std/utility.h
+++ b/include/blt/std/utility.h
@@ -96,6 +96,7 @@ namespace blt
 
 
 #if defined(__GNUC__) || defined(__llvm__)
+    #define BLT_UNREACHABLE __builtin_unreachable()
     #define BLT_ATTRIB_NO_INLINE __attribute__ ((noinline))
     /**
      * means that the return value is solely a function of the arguments,
@@ -114,12 +115,19 @@ namespace blt
 #else
     #if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
         #define BLT_ATTRIB_NO_INLINE __declspec(noinline)
+        #define BLT_UNREACHABLE __assume(false)
     #else
         #define BLT_ATTRIB_NO_INLINE
+        #define BLT_UNREACHABLE
     #endif
     #define BLT_ATTRIB_CONST
     #define BLT_ATTRIB_PURE
 #endif
+
+#if __cplusplus > 202002L
+    #undef BLT_UNREACHABLE
+    #define BLT_UNREACHABLE std::unreachable()
+#endif
     
     template<typename T>
     BLT_ATTRIB_NO_INLINE void black_box(const T& val)
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