diff --git a/spot/twa/twagraph.cc b/spot/twa/twagraph.cc
index 93d042521..c96bfc102 100644
--- a/spot/twa/twagraph.cc
+++ b/spot/twa/twagraph.cc
@@ -331,7 +331,35 @@ namespace spot
                                       || (a.dst == a.src && b.dst == b.src))
                                      && a.data() == b.data()); }))
             {
-              remap[i] = j;
+              remap[i] = (remap[j] != -1U) ? remap[j] : j;
+
+              // Because of the special self-loop tests we use above,
+              // it's possible that i can be mapped to remap[j] even
+              // if j was last compatible states found.  Consider the
+              // following cases, taken from an actual test case:
+              // 18 is equal to 5, 35 is equal to 18, but 35 is not
+              // equal to 5.
+              //
+              // State: 5
+              // [0&1&2] 8 {3}
+              // [!0&1&2] 10 {1}
+              // [!0&!1&!2] 18 {1}
+              // [!0&!1&2] 19 {1}
+              // [!0&1&!2] 20 {1}
+              //
+              // State: 18
+              // [0&1&2] 8 {3}
+              // [!0&1&2] 10 {1}
+              // [!0&!1&!2] 18 {1} // self-loop
+              // [!0&!1&2] 19 {1}
+              // [!0&1&!2] 20 {1}
+              //
+              // State: 35
+              // [0&1&2] 8 {3}
+              // [!0&1&2] 10 {1}
+              // [!0&!1&!2] 35 {1} // self-loop
+              // [!0&!1&2] 19 {1}
+              // [!0&1&!2] 20 {1}
               break;
             }
           }
diff --git a/tests/python/mergedge.py b/tests/python/mergedge.py
index b0325603e..e55bdabf2 100644
--- a/tests/python/mergedge.py
+++ b/tests/python/mergedge.py
@@ -83,3 +83,86 @@ assert aut.num_edges() == 4
 assert aut.num_states() == 2
 assert spot.is_deterministic(aut)
 assert aut.prop_complete()
+
+
+aa = spot.automaton("""
+HOA: v1 States: 41 Start: 0 AP: 3 "allfinished" "finished_0"
+"finished_1" acc-name: parity max odd 4 Acceptance: 4 Inf(3) | (Fin(2)
+& (Inf(1) | Fin(0))) properties: trans-labels explicit-labels
+trans-acc colored properties: deterministic --BODY-- State: 0
+[!0&!1&!2] 1 {1} [!0&!1&2] 2 {1} [!0&1&!2] 3 {1} [!0&1&2] 4 {1}
+[0&!1&!2] 5 {1} [0&!1&2] 6 {1} [0&1&!2] 7 {1} [0&1&2] 8 {1} State: 1
+[!0&!1&!2] 1 {1} [!0&!1&2] 2 {1} [0&1&!2] 7 {1} [0&1&2] 8 {1}
+[!0&1&!2] 9 {1} [!0&1&2] 10 {1} [0&!1&!2] 11 {1} [0&!1&2] 12 {1}
+State: 2 [!0&!1&2] 2 {1} [0&1&!2] 7 {1} [0&1&2] 8 {1} [!0&1&2] 10 {1}
+[0&!1&!2] 11 {1} [0&!1&2] 12 {1} [!0&!1&!2] 13 {1} [!0&1&!2] 14 {1}
+State: 3 [0&1&!2] 7 {1} [0&1&2] 8 {1} [!0&1&!2] 9 {1} [!0&1&2] 10 {1}
+[0&!1&!2] 11 {1} [0&!1&2] 12 {1} [!0&!1&!2] 15 {1} [!0&!1&2] 16 {1}
+State: 4 [0&1&!2] 7 {1} [0&1&2] 8 {1} [!0&1&2] 10 {1} [0&!1&!2] 11 {1}
+[0&!1&2] 12 {1} [!0&1&!2] 14 {1} [!0&!1&2] 16 {1} [!0&!1&!2] 17 {1}
+State: 5 [0&1&2] 8 {3} [!0&1&2] 10 {1} [!0&!1&!2] 18 {1} [!0&!1&2] 19
+{1} [!0&1&!2] 20 {1} State: 6 [0&1&2] 8 {1} [!0&1&2] 10 {1} [!0&!1&2]
+19 {1} [!0&1&!2] 20 {1} [!0&!1&!2] 21 {1} State: 7 [0&1&2] 8 {3}
+[!0&1&2] 10 {1} [!0&!1&2] 19 {1} [!0&1&!2] 20 {1} [!0&!1&!2] 22 {1}
+State: 8 [!0&!1&!2] 5 {1} [0&1&2] 8 {3} [!0&1&2] 10 {1} [!0&!1&2] 19
+{1} [!0&1&!2] 20 {1} State: 9 [0&!1&!2] 5 {1} [0&1&!2] 7 {1} [0&1&2] 8
+{1} [!0&1&!2] 9 {1} [!0&1&2] 10 {1} [0&!1&2] 12 {1} [!0&!1&!2] 23 {1}
+[!0&!1&2] 24 {1} State: 10 [0&!1&!2] 5 {3} [0&1&!2] 7 {3} [0&1&2] 8
+{3} [!0&1&2] 10 {2} [0&!1&2] 12 {3} [!0&1&!2] 14 {1} [!0&!1&2] 24 {1}
+[!0&!1&!2] 25 {1} State: 11 [0&1&2] 8 {3} [!0&1&2] 10 {1} [!0&!1&2] 19
+{1} [!0&!1&!2] 26 {1} [!0&1&!2] 27 {1} State: 12 [0&1&2] 8 {3}
+[!0&1&2] 10 {1} [!0&!1&2] 19 {1} [!0&1&!2] 27 {1} [!0&!1&!2] 28 {1}
+State: 13 [!0&!1&2] 2 {1} [0&1&!2] 7 {1} [0&1&2] 8 {1} [!0&1&2] 10 {1}
+[0&!1&!2] 11 {1} [0&!1&2] 12 {1} [!0&!1&!2] 13 {1} [!0&1&!2] 14 {1}
+State: 14 [0&!1&!2] 5 {3} [0&1&!2] 7 {3} [0&1&2] 8 {3} [!0&1&2] 10 {2}
+[0&!1&2] 12 {3} [!0&1&!2] 14 {1} [!0&!1&2] 24 {2} [!0&!1&!2] 29 {1}
+State: 15 [0&1&!2] 7 {1} [0&1&2] 8 {1} [!0&1&!2] 9 {1} [!0&1&2] 10 {1}
+[0&!1&!2] 11 {1} [0&!1&2] 12 {1} [!0&!1&!2] 15 {1} [!0&!1&2] 16 {1}
+State: 16 [0&1&!2] 7 {1} [0&1&2] 8 {1} [!0&1&2] 10 {1} [0&!1&!2] 11
+{1} [0&!1&2] 12 {1} [!0&1&!2] 14 {1} [!0&!1&2] 16 {1} [!0&!1&!2] 17
+{1} State: 17 [0&1&!2] 7 {1} [0&1&2] 8 {1} [!0&1&2] 10 {1} [0&!1&!2]
+11 {1} [0&!1&2] 12 {1} [!0&1&!2] 14 {1} [!0&!1&2] 16 {1} [!0&!1&!2] 17
+{1} State: 18 [0&1&2] 8 {3} [!0&1&2] 10 {1} [!0&!1&!2] 18 {1}
+[!0&!1&2] 19 {1} [!0&1&!2] 20 {1} State: 19 [0&1&!2] 7 {3} [0&1&2] 8
+{3} [!0&!1&2] 19 {1} [!0&!1&!2] 30 {1} [!0&1&!2] 31 {1} [!0&1&2] 32
+{1} State: 20 [0&1&2] 8 {3} [0&!1&2] 12 {1} [!0&1&!2] 20 {1} [!0&1&2]
+32 {1} [!0&!1&!2] 33 {1} [!0&!1&2] 34 {1} State: 21 [0&1&2] 8 {1}
+[!0&1&2] 10 {1} [!0&!1&!2] 18 {1} [!0&!1&2] 19 {1} [!0&1&!2] 20 {1}
+State: 22 [0&1&2] 8 {3} [!0&1&2] 10 {1} [!0&!1&2] 19 {1} [!0&1&!2] 20
+{1} [!0&!1&!2] 35 {1} State: 23 [0&!1&!2] 5 {1} [0&1&!2] 7 {1} [0&1&2]
+8 {1} [!0&1&!2] 9 {1} [!0&1&2] 10 {1} [0&!1&2] 12 {1} [!0&!1&!2] 23
+{1} [!0&!1&2] 24 {1} State: 24 [0&!1&!2] 5 {3} [0&1&!2] 7 {3} [0&1&2]
+8 {3} [!0&1&2] 10 {2} [0&!1&2] 12 {3} [!0&1&!2] 14 {2} [!0&!1&2] 24
+{1} [!0&!1&!2] 25 {1} State: 25 [0&!1&!2] 5 {3} [0&1&!2] 7 {3} [0&1&2]
+8 {3} [!0&1&2] 10 {2} [0&!1&2] 12 {3} [!0&1&!2] 14 {2} [!0&!1&2] 24
+{1} [!0&!1&!2] 25 {1} State: 26 [0&1&2] 8 {3} [!0&1&2] 10 {1}
+[!0&!1&2] 19 {1} [!0&!1&!2] 26 {1} [!0&1&!2] 27 {1} State: 27 [0&1&2]
+8 {3} [0&!1&2] 12 {3} [!0&1&!2] 27 {1} [!0&1&2] 32 {1} [!0&!1&!2] 36
+{1} [!0&!1&2] 37 {1} State: 28 [0&1&2] 8 {3} [!0&1&2] 10 {1} [!0&!1&2]
+19 {1} [!0&!1&!2] 26 {1} [!0&1&!2] 27 {1} State: 29 [0&!1&!2] 5 {3}
+[0&1&!2] 7 {3} [0&1&2] 8 {3} [!0&1&2] 10 {2} [0&!1&2] 12 {3} [!0&1&!2]
+14 {1} [!0&!1&2] 24 {2} [!0&!1&!2] 29 {1} State: 30 [0&1&!2] 7 {3}
+[0&1&2] 8 {3} [!0&!1&2] 19 {1} [!0&!1&!2] 30 {1} [!0&1&!2] 31 {1}
+[!0&1&2] 32 {1} State: 31 [0&!1&!2] 5 {3} [0&1&!2] 7 {3} [0&1&2] 8 {3}
+[0&!1&2] 12 {3} [!0&1&!2] 31 {1} [!0&1&2] 32 {2} [!0&!1&2] 37 {2}
+[!0&!1&!2] 38 {1} State: 32 [0&!1&!2] 5 {3} [0&1&!2] 7 {3} [0&1&2] 8
+{3} [0&!1&2] 12 {3} [!0&1&!2] 31 {1} [!0&1&2] 32 {2} [!0&!1&2] 37 {1}
+[!0&!1&!2] 39 {1} State: 33 [0&1&2] 8 {3} [0&!1&2] 12 {1} [!0&1&!2] 20
+{1} [!0&1&2] 32 {1} [!0&!1&!2] 33 {1} [!0&!1&2] 34 {1} State: 34
+[0&1&!2] 7 {3} [0&1&2] 8 {3} [0&!1&!2] 11 {1} [0&!1&2] 12 {1}
+[!0&1&!2] 31 {1} [!0&1&2] 32 {1} [!0&!1&2] 34 {1} [!0&!1&!2] 40 {1}
+State: 35 [0&1&2] 8 {3} [!0&1&2] 10 {1} [!0&!1&2] 19 {1} [!0&1&!2] 20
+{1} [!0&!1&!2] 35 {1} State: 36 [0&1&2] 8 {3} [0&!1&2] 12 {3}
+[!0&1&!2] 27 {1} [!0&1&2] 32 {1} [!0&!1&!2] 36 {1} [!0&!1&2] 37 {1}
+State: 37 [0&!1&!2] 5 {3} [0&1&!2] 7 {3} [0&1&2] 8 {3} [0&!1&2] 12 {3}
+[!0&1&!2] 31 {2} [!0&1&2] 32 {2} [!0&!1&2] 37 {1} [!0&!1&!2] 39 {1}
+State: 38 [0&!1&!2] 5 {3} [0&1&!2] 7 {3} [0&1&2] 8 {3} [0&!1&2] 12 {3}
+[!0&1&!2] 31 {1} [!0&1&2] 32 {2} [!0&!1&2] 37 {2} [!0&!1&!2] 38 {1}
+State: 39 [0&!1&!2] 5 {3} [0&1&!2] 7 {3} [0&1&2] 8 {3} [0&!1&2] 12 {3}
+[!0&1&!2] 31 {2} [!0&1&2] 32 {2} [!0&!1&2] 37 {1} [!0&!1&!2] 39 {1}
+State: 40 [0&1&!2] 7 {3} [0&1&2] 8 {3} [0&!1&!2] 11 {1} [0&!1&2] 12
+{1} [!0&1&!2] 31 {1} [!0&1&2] 32 {1} [!0&!1&2] 34 {1} [!0&!1&!2] 40
+{1} --END--""")
+aa.merge_states()
+# This used to cause a segfault reported by Philipp.
+print(aa.to_str())