diff --git a/awk.h b/awk.h
index 363e440..853163a 100644
--- a/awk.h
+++ b/awk.h
@@ -1323,12 +1323,25 @@ DEREF(NODE *r)
 #define get_lhs(n, r)	 (n)->type == Node_var && ! var_uninitialized(n) ? \
 				&((n)->var_value) : r_get_lhs((n), (r))
 
+#define MEMDEBUG
+
+#ifdef MEMDEBUG
+
+extern void *r_getblock(int id);
+extern void r_freeblock(void *, int id);
+#define getblock(p, id, ty)	(void) (p = r_getblock(id))
+#define freeblock(p, id)	(void) (r_freeblock(p, id))
+
+#else
+
 #define getblock(p, id, ty)  (void) ((p = (ty) nextfree[id].freep) ? \
 			(ty) (nextfree[id].freep = ((struct block_item *) p)->freep) \
 			: (p = (ty) more_blocks(id)))
 #define freeblock(p, id)	 (void) (((struct block_item *) p)->freep = nextfree[id].freep, \
 					nextfree[id].freep = (struct block_item *) p)
 
+#endif /* MEMDEBUG */
+
 #define getnode(n)	getblock(n, BLOCK_NODE, NODE *)
 #define freenode(n)	freeblock(n, BLOCK_NODE)
 
diff --git a/node.c b/node.c
index 9574c3e..049acc1 100644
--- a/node.c
+++ b/node.c
@@ -1034,6 +1034,31 @@ struct block_header nextfree[BLOCK_MAX] = {
 #endif
 };
 
+#ifdef MEMDEBUG
+
+void *
+r_getblock(int id)
+{
+	void *res;
+	emalloc(res, void *, nextfree[id].size, "getblock");
+#if 0
+	if (id == BLOCK_NODE)
+		fprintf(stderr, "allocated node %p\n", res);
+#endif
+	return res;
+}
+
+void
+r_freeblock(void *p, int id)
+{
+#if 0
+	if (id == BLOCK_NODE)
+		fprintf(stderr, "freeing node %p\n", p);
+#endif
+	free(p);
+}
+
+#else
 
 /* more_blocks --- get more blocks of memory and add to the free list;
 	size of a block must be >= sizeof(struct block_item)
@@ -1064,3 +1089,5 @@ more_blocks(int id)
 	nextfree[id].freep = freep->freep;
 	return freep;
 }
+
+#endif