Block is always marked used as used, no need to mark it inside a split try.

src/custom_malloc.c

@@ -97,8 +97,6 @@ void * custom_ahmalloc(allocator_t* allocator, heap_t* heap, size_t size) {
 
         if(new_size > min_split_size) {
             split(allocator, heap, ptr, size);
-        } else {
-            mark_used(ptr);
         }
 #else
         mark_used(ptr);