diff --git a/test-treap.c b/test-treap.c
index cdba5111e1..ab8c951c6e 100644
--- a/test-treap.c
+++ b/test-treap.c
@@ -38,9 +38,14 @@ int main(int argc, char *argv[])
 		usage("test-treap < ints");
 
 	while (strbuf_getline(&sb, stdin, '\n') != EOF) {
-		item = node_alloc(1);
-		strtonode(node_pointer(item), sb.buf);
-		treap_insert(&root, node_pointer(item));
+		struct int_node *node = node_pointer(node_alloc(1));
+
+		item = node_offset(node);
+		strtonode(node, sb.buf);
+		node = treap_insert(&root, node_pointer(item));
+		if (node_offset(node) != item)
+			die("inserted %"PRIu32" in place of %"PRIu32"",
+				node_offset(node), item);
 	}
 
 	item = node_offset(treap_first(&root));
diff --git a/vcs-svn/trp.h b/vcs-svn/trp.h
index ee35c688a0..c32b9184e9 100644
--- a/vcs-svn/trp.h
+++ b/vcs-svn/trp.h
@@ -188,11 +188,12 @@ a_attr uint32_t MAYBE_UNUSED a_pre##insert_recurse(uint32_t cur_node, uint32_t i
 		return ret; \
 	} \
 } \
-a_attr void MAYBE_UNUSED a_pre##insert(struct trp_root *treap, a_type *node) \
+a_attr a_type *MAYBE_UNUSED a_pre##insert(struct trp_root *treap, a_type *node) \
 { \
 	uint32_t offset = trpn_offset(a_base, node); \
 	trp_node_new(a_base, a_field, offset); \
 	treap->trp_root = a_pre##insert_recurse(treap->trp_root, offset); \
+	return trpn_pointer(a_base, offset); \
 } \
 a_attr uint32_t MAYBE_UNUSED a_pre##remove_recurse(uint32_t cur_node, uint32_t rem_node) \
 { \
diff --git a/vcs-svn/trp.txt b/vcs-svn/trp.txt
index eb4c191875..5ca6b42edb 100644
--- a/vcs-svn/trp.txt
+++ b/vcs-svn/trp.txt
@@ -21,7 +21,9 @@ The caller:
 
 . Allocates a `struct trp_root` variable and sets it to {~0}.
 
-. Adds new nodes to the set using `foo_insert`.
+. Adds new nodes to the set using `foo_insert`.  Any pointers
+  to existing nodes cannot be relied upon any more, so the caller
+  might retrieve them anew with `foo_pointer`.
 
 . Can find a specific item in the set using `foo_search`.
 
@@ -73,10 +75,14 @@ int (*cmp)(node_type \*a, node_type \*b)
 and returning a value less than, equal to, or greater than zero
 according to the result of comparison.
 
-void foo_insert(struct trp_root *treap, node_type \*node)::
+node_type {asterisk}foo_insert(struct trp_root *treap, node_type \*node)::
 
 	Insert node into treap.  If inserted multiple times,
 	a node will appear in the treap multiple times.
++
+The return value is the address of the node within the treap,
+which might differ from `node` if `pool_alloc` had to call
+`realloc` to expand the pool.
 
 void foo_remove(struct trp_root *treap, node_type \*node)::