diff --git a/include/mimalloc-internal.h b/include/mimalloc-internal.h
index cf5b6783..1333c80f 100644
--- a/include/mimalloc-internal.h
+++ b/include/mimalloc-internal.h
@@ -20,14 +20,17 @@ terms of the MIT license. A copy of the license can be found in the file
 #if defined(_MSC_VER)
 #pragma warning(disable:4127)   // suppress constant conditional warning (due to MI_SECURE paths)
 #define mi_decl_noinline        __declspec(noinline)
+#define mi_decl_always_inline   __forceinline
 #define mi_decl_thread          __declspec(thread)
 #define mi_decl_cache_align     __declspec(align(MI_CACHE_LINE))
 #elif (defined(__GNUC__) && (__GNUC__ >= 3)) || defined(__clang__) // includes clang and icc
 #define mi_decl_noinline        __attribute__((noinline))
+#define mi_decl_always_inline   __attribute__((always_inline))
 #define mi_decl_thread          __thread
 #define mi_decl_cache_align     __attribute__((aligned(MI_CACHE_LINE)))
 #else
 #define mi_decl_noinline
+#define mi_decl_always_inline   inline
 #define mi_decl_thread          __thread        // hope for the best :-)
 #define mi_decl_cache_align
 #endif
diff --git a/include/mimalloc.h b/include/mimalloc.h
index 756e516c..f90af4a3 100644
--- a/include/mimalloc.h
+++ b/include/mimalloc.h
@@ -271,6 +271,8 @@ mi_decl_export int mi_reserve_huge_os_pages_at(size_t pages, int numa_node, size
 mi_decl_export int  mi_reserve_os_memory(size_t size, bool commit, bool allow_large) mi_attr_noexcept;
 mi_decl_export bool mi_manage_os_memory(void* start, size_t size, bool is_committed, bool is_large, bool is_zero, int numa_node) mi_attr_noexcept;
 
+mi_decl_export size_t mi_get_current_threadid(void) mi_attr_noexcept;
+mi_decl_export void   mi_unsafe_free_with_threadid(void* p, size_t current_tid ) mi_attr_noexcept;
 
 // deprecated
 mi_decl_export int  mi_reserve_huge_os_pages(size_t pages, double max_secs, size_t* pages_reserved) mi_attr_noexcept;
diff --git a/src/alloc.c b/src/alloc.c
index d9b6dd60..4d0d9e59 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -475,14 +475,12 @@ static inline mi_segment_t* mi_checked_ptr_segment(const void* p, const char* ms
   return segment;
 }
 
-
-// Free a block
-void mi_free(void* p) mi_attr_noexcept
+// Free a block with a known threadid
+static mi_decl_always_inline void _mi_free_with_threadid(void* p, mi_threadid_t tid) mi_attr_noexcept
 {
   const mi_segment_t* const segment = mi_checked_ptr_segment(p,"mi_free");
   if (mi_unlikely(segment == NULL)) return; 
 
-  const mi_threadid_t tid = _mi_thread_id();
   mi_page_t* const page = _mi_segment_page_of(segment, p);
   mi_block_t* const block = (mi_block_t*)p;
 
@@ -507,6 +505,25 @@ void mi_free(void* p) mi_attr_noexcept
   }
 }
 
+// Get the current thread id
+size_t mi_get_current_threadid(void) mi_attr_noexcept {
+  return _mi_thread_id();
+}
+
+// Free a block passing the current thread id explicitly
+void mi_unsafe_free_with_threadid(void* p, size_t current_tid ) mi_attr_noexcept 
+{
+  mi_assert(current_tid == _mi_thread_id());
+  _mi_free_with_threadid(p,current_tid);
+}
+
+
+// Free a block
+void mi_free(void* p) mi_attr_noexcept {
+  _mi_free_with_threadid(p, _mi_thread_id());
+}
+
+
 bool _mi_free_delayed_block(mi_block_t* block) {
   // get segment and page
   const mi_segment_t* const segment = _mi_ptr_segment(block);