diff --git a/include/mimalloc.h b/include/mimalloc.h
index 1f80027..3c10a65 100644
--- a/include/mimalloc.h
+++ b/include/mimalloc.h
@@ -121,7 +121,6 @@ mi_decl_export void mi_thread_stats_print(FILE* out) mi_attr_noexcept;
 typedef void (mi_deferred_free_fun)(bool force, unsigned long long heartbeat);
 mi_decl_export void mi_register_deferred_free(mi_deferred_free_fun* deferred_free) mi_attr_noexcept;
 
-
 // ------------------------------------------------------
 // Aligned allocation
 // ------------------------------------------------------
@@ -196,6 +195,8 @@ typedef bool (mi_cdecl mi_block_visit_fun)(const mi_heap_t* heap, const mi_heap_
 
 mi_decl_export bool mi_heap_visit_blocks(const mi_heap_t* heap, bool visit_all_blocks, mi_block_visit_fun* visitor, void* arg);
 
+mi_decl_export bool mi_is_in_heap_region(const void* p) mi_attr_noexcept;
+
 // ------------------------------------------------------
 // Convenience
 // ------------------------------------------------------
diff --git a/src/memory.c b/src/memory.c
index 030541a..83e90b0 100644
--- a/src/memory.c
+++ b/src/memory.c
@@ -104,6 +104,16 @@ static size_t mi_good_commit_size(size_t size) {
   return _mi_align_up(size, _mi_os_large_page_size());  
 }
 
+// Return if a pointer points into a region reserved by us.
+bool mi_is_in_heap_region(const void* p) {
+  size_t count = mi_atomic_read(&regions_count);
+  for (size_t i = 0; i < count; i++) {
+    uint8_t* start = (uint8_t*)mi_atomic_read_ptr(&regions[i].start);
+    if (start != NULL && (uint8_t*)p >= start && (uint8_t*)p < start + MI_REGION_SIZE) return true;
+  }
+  return false;
+}
+
 /* ----------------------------------------------------------------------------
 Commit from a region
 -----------------------------------------------------------------------------*/