diff --git a/src/macros.h b/src/macros.h
index ca54cb4..ae784d6 100644
--- a/src/macros.h
+++ b/src/macros.h
@@ -353,3 +353,14 @@
 #  endif
 # endif
 #endif
+
+/*
+ * In a hashtab item "hi_key" points to "di_key" in a dictitem.
+ * This avoids adding a pointer to the hashtab item.
+ * DI2HIKEY() converts a dictitem pointer to a hashitem key pointer.
+ * HIKEY2DI() converts a hashitem key pointer to a dictitem pointer.
+ * HI2DI() converts a hashitem pointer to a dictitem pointer.
+ */
+# define DI2HIKEY(di) ((di)->di_key)
+# define HIKEY2DI(p)  ((dictitem_T *)(p - offsetof(dictitem_T, di_key)))
+# define HI2DI(hi)     HIKEY2DI((hi)->hi_key)