diff --git a/redo/ptrarray.c b/redo/ptrarray.c
index 6a7b36b3..b8abc8dd 100644
--- a/redo/ptrarray.c
+++ b/redo/ptrarray.c
@@ -21,17 +21,12 @@ void ptrArrayDestroy(struct ptrArray *p)
 
 void ptrArrayAppend(struct ptrArray *p, void *d)
 {
-	if (p->len >= p->cap) {
-		p->cap += grow;
-		p->ptrs = (void **) uiRealloc(p->ptrs, p->cap * sizeof (void *), "void *[]");
-	}
-	p->ptrs[p->len] = d;
-	p->len++;
+	ptrArrayInsertBefore(p, p->len, d);
 }
 
 void ptrArrayInsertBefore(struct ptrArray *p, uintmax_t i, void *d)
 {
-	if (i >= p->len)
+	if (i > p->len)
 		complain("index out of range in ptrArrayInsertBefore()");
 	if (p->len >= p->cap) {
 		p->cap += grow;