diff --git a/spot/twa/acc.cc b/spot/twa/acc.cc
index b1c4a0d73..be3837658 100644
--- a/spot/twa/acc.cc
+++ b/spot/twa/acc.cc
@@ -479,9 +479,9 @@ namespace spot
           s = 5;
         }
       else if (mainop != highop)
-      {
-        return false;
-      }
+        {
+          return false;
+        }
       while (s)
         {
           auto op = code[--s].sub.op;
@@ -494,7 +494,10 @@ namespace spot
               acc_cond::mark_t inf(0U);
 
               if (op == singleop && m.count() != 1)
-                return false;
+                {
+                  pairs.clear();
+                  return false;
+                }
               for (unsigned mark: m.sets())
                 {
                   if (op == acc_cond::acc_op::Fin)
@@ -507,7 +510,10 @@ namespace spot
           else
             {
               if (op != lowop || size != 4)
-                return false;
+                {
+                  pairs.clear();
+                  return false;
+                }
 
               auto o1 = code[--s].sub.op;
               auto m1 = code[--s].mark;
@@ -527,7 +533,10 @@ namespace spot
                   || o2 != acc_cond::acc_op::Inf
                   || m1.count() != 1
                   || m2.count() != 1)
-                return false;
+                {
+                  pairs.clear();
+                  return false;
+                }
               pairs.emplace_back(m1, m2);
             }
         }
diff --git a/spot/twaalgos/totgba.cc b/spot/twaalgos/totgba.cc
index d74d1d27c..01bbc0c5d 100644
--- a/spot/twaalgos/totgba.cc
+++ b/spot/twaalgos/totgba.cc
@@ -331,8 +331,8 @@ namespace spot
     }();
 
     std::vector<acc_cond::rs_pair> pairs;
-    in->acc().is_streett_like(pairs);
-    if (min == 0 || min > pairs.size())
+    bool res = in->acc().is_streett_like(pairs);
+    if (!res || min == 0 || min > pairs.size())
       return nullptr;
     else
       return streett_to_generalized_buchi(in);