diff --git a/darray.h b/darray.h
index c9035b74b6..dc9d282be2 100644
--- a/darray.h
+++ b/darray.h
@@ -72,6 +72,20 @@
     (*(ptr_to_ary))->meta.size++; \
 } while (0)
 
+/* Removes the element at idx and replaces it with the last element.
+ * ptr_to_ary and idx is evaluated multiple times.
+ * Warning: not bounds checked.
+ *
+ * void rb_darray_swap_remove(rb_darray(T) *ptr_to_ary, size_t idx);
+ */
+#define rb_darray_swap_remove(ptr_to_ary, idx) do { \
+    size_t _darray_size = rb_darray_size(*(ptr_to_ary)); \
+    if ((idx) != _darray_size - 1) { \
+        (*(ptr_to_ary))->data[idx] = (*(ptr_to_ary))->data[_darray_size - 1]; \
+    } \
+    (*(ptr_to_ary))->meta.size--; \
+} while (0)
+
 // Iterate over items of the array in a for loop
 //
 #define rb_darray_foreach(ary, idx_name, elem_ptr_var) \