diff --git a/main.c b/main.c
index 9b29025..d7cb5c5 100644
--- a/main.c
+++ b/main.c
@@ -346,6 +346,7 @@ int main(int argc, char *argv[]) {
     printf("\nB node: %u/%u\n", tt_ptr_idx(B), tt_ptr_tag(B));
     tt_dump_arena_dot_styled("B", B, &a, TT_STYLE_TEXT_LABELS);
     tt_dump_routingtable(&a, B, 0);
+    printf("(calling tt_trie_subtract_set now)\n");
     tt_node_ptr_t C = tt_trie_subtract_set(&a, A, B);
     tt_arena_flush(&a);
     tt_dump_arena_dot_styled("Cpredrop", C, &a, TT_STYLE_TEXT_LABELS);
@@ -354,6 +355,7 @@ int main(int argc, char *argv[]) {
     printf("\nC node: %u/%u\n", tt_ptr_idx(C), tt_ptr_tag(C));
     tt_arena_flush(&a);
     tt_dump_arena_dot_styled("Cpostdrop", C, &a, TT_STYLE_TEXT_LABELS | TT_STYLE_HIDE_DETAILS);
+    tt_dump_routingtable(&a, C, 0);
     tt_replace(&a, &C, tt_trie_relabel_const(&a, C, a_set));
     printf("\nC node post relabel: %u/%u\n", tt_ptr_idx(C), tt_ptr_tag(C));
     tt_arena_flush(&a);
diff --git a/route.c b/route.c
index 3ed2bde..f70e177 100644
--- a/route.c
+++ b/route.c
@@ -143,17 +143,17 @@ static inline tt_node_ptr_t expand(tt_arena_t *a, tt_node_ptr_t tailnode) {
 }
 
 static inline tt_node_ptr_t collapse(tt_arena_t *a, tt_node_ptr_t n) {
+  /* This is a hand-inlined version of rupdate followed by rlookup of
+     TT_EOS, effectively undoing expand(). */
   if (tt_ptr_tag(n) == TT_TAG_BRANCH) {
-    tt_node_ptr_t w = TT_BRANCH_WILDCARD(a,n);
     tt_node_ptr_t o = TT_BRANCH_OTHERS(a,n);
-    if (tt_ptr_tag(w) == TT_TAG_TAIL &&
-	tt_ptr_tag(o) == TT_TAG_DICT &&
-	TT_DICT_SIZE(a,o) == 1) {
-      tt_node_ptr_t root = TT_DICT_ROOT(a,o);
-      assert(tt_ptr_tag(root) == TT_TAG_LEAF);
-      if (TT_LEAF_ATOM(a,root) == TT_EOS &&
-	  TT_LEAF_TRIE(a,root) == TT_TAIL_TRIE(a,w)) {
-	return w;
+    if (tt_ptr_tag(o) == TT_TAG_DICT) {
+      tt_node_ptr_t eos_trie = tt_dict_get(a, o, TT_EOS);
+      if (!TT_NO_PTR_P(eos_trie)) {
+	tt_node_ptr_t w = TT_BRANCH_WILDCARD(a,n);
+	if (tt_ptr_tag(w) == TT_TAG_TAIL && eos_trie == TT_TAIL_TRIE(a,w)) {
+	  return rbranch(a, w, RET_IF_NO_PTR(tt_dict_remove(a, o, TT_EOS)));
+	}
       }
     }
   }
@@ -209,6 +209,12 @@ tt_node_ptr_t tt_trie_combine(tt_arena_t *a,
 	  tt_drop(a, trie1);
 	  return 0;
 	}
+	/* printf("descending into key %d, trie1 %u/%u trie2 %u/%u\n", */
+	/*        key, */
+	/*        tt_ptr_idx(trie1), */
+	/*        tt_ptr_tag(trie1), */
+	/*        tt_ptr_idx(trie2), */
+	/*        tt_ptr_tag(trie2)); */
 	new_trie = g(trie1, trie2); /* already grabbed */
 	tt_drop(a, trie1);
 	tt_drop(a, trie2);