diff --git a/NEWS b/NEWS
index da6b9f1be..8cb8e4a55 100644
--- a/NEWS
+++ b/NEWS
@@ -12,6 +12,12 @@ New in spot 2.5.0.dev (not yet released)
 
   - iar() and iar_maybe() properly handle Rabin-like conditions.
 
+  - is_generalized_rabin() had a typo that caused some non-simplified
+    acceptance conditions like Fin(0)|(Fin(0)&Inf(1)) to be
+    incorrectly detecteded as generalized-Rabin 2 0 1 and then output
+    as Fin(0)|(Fin(1)&Inf(2)) instead.  Likewise for
+    is_generalized_streett
+
 New in spot 2.5 (2018-01-20)
 
   Build:
diff --git a/spot/twa/acc.cc b/spot/twa/acc.cc
index 2de0d221e..0c36625b5 100644
--- a/spot/twa/acc.cc
+++ b/spot/twa/acc.cc
@@ -666,7 +666,7 @@ namespace spot
     auto s = code_.back().sub.size;
     acc_cond::mark_t seen_fin = 0U;
     acc_cond::mark_t seen_inf = 0U;
-    // Each pairs is the position of a Fin followed
+    // Each pair is the position of a Fin followed
     // by the number of Inf.
     std::map<unsigned, unsigned> p;
     while (s)
@@ -697,7 +697,7 @@ namespace spot
             unsigned i = m2.count();
             // If we have seen this pair already, it must have the
             // same size.
-            if (p.emplace(m1.max_set(), i).first->second != i)
+            if (p.emplace(m1.max_set() - 1, i).first->second != i)
               return false;
             assert(i > 0);
             unsigned j = m1.max_set(); // == n+1
@@ -705,7 +705,6 @@ namespace spot
               if (!m2.has(j++))
                 return false;
             while (--i);
-
             seen_fin |= m1;
             seen_inf |= m2;
           }
@@ -715,8 +714,10 @@ namespace spot
             for (auto s: m1.sets())
               // If we have seen this pair already, it must have the
               // same size.
-              if (p.emplace(s, 0U).first->second != 0U)
-                return false;
+              {
+                if (p.emplace(s, 0U).first->second != 0U)
+                  return false;
+              }
             seen_fin |= m1;
           }
         else
@@ -777,7 +778,7 @@ namespace spot
             unsigned i = m2.count();
             // If we have seen this pair already, it must have the
             // same size.
-            if (p.emplace(m1.max_set(), i).first->second != i)
+            if (p.emplace(m1.max_set() - 1, i).first->second != i)
               return false;
             assert(i > 0);
             unsigned j = m1.max_set(); // == n+1
diff --git a/tests/core/accsimpl.test b/tests/core/accsimpl.test
index 773dc85af..1feb8fed4 100755
--- a/tests/core/accsimpl.test
+++ b/tests/core/accsimpl.test
@@ -28,3 +28,26 @@ set -e
 ltlcross -f FGa \
   'ltl2tgba -G -D %f | autfilt --complement >%O' \
   'ltl2tgba -G -D %f | autfilt --complement | autfilt --simplify-acceptance >%O'
+
+
+cat >325 <<EOF
+HOA: v1
+States: 1
+Start: 0
+AP: 2 "a" "b"
+acc-name: Rabin 3
+Acceptance: 6 (Fin(0) & Inf(1)) | (Fin(2) & Inf(3)) | (Fin(4) & Inf(5))
+properties: trans-labels explicit-labels trans-acc complete
+properties: deterministic
+--BODY--
+State: 0
+[!0&!1] 0 {0 4}
+[!0&1] 0 {0 3 4}
+[0&!1] 0 {2 5}
+[0&1] 0 {1 2 5}
+--END--
+EOF
+
+autfilt --simplify-acceptance 325 > 325s
+exp='4 Fin(0) | (Fin(0) & Inf(1)) | (Fin(2) & Inf(3))'
+test "$exp" = "`autfilt --stats='%a %g' 325s`"