diff --git a/src/ltlast/binop.cc b/src/ltlast/binop.cc
index 7cf62be89..fe89c9ea2 100644
--- a/src/ltlast/binop.cc
+++ b/src/ltlast/binop.cc
@@ -258,17 +258,24 @@ namespace spot
 	case EConcat:
 	  //   - 0 <>-> Exp = 0
 	  //   - 1 <>-> Exp = Exp
-	  if (first == constant::false_instance())
-	    return second;
+	  //   - Exp <>-> 0 = 0
 	  if (first == constant::true_instance())
+	    return second;
+	  if (first == constant::false_instance())
 	    {
 	      second->destroy();
 	      return first;
 	    }
+	  if (second == constant::false_instance())
+	    {
+	      first->destroy();
+	      return second;
+	    }
 	  break;
 	case UConcat:
 	  //   - 0 []-> Exp = 1
 	  //   - 1 []-> Exp = Exp
+	  //   - Exp []-> 1 = 1
 	  if (first == constant::false_instance())
 	    return constant::true_instance();
 	  if (first == constant::true_instance())
@@ -276,6 +283,11 @@ namespace spot
 	      second->destroy();
 	      return first;
 	    }
+	  if (second == constant::true_instance())
+	    {
+	      first->destroy();
+	      return second;
+	    }
 	  break;
 	}
 
diff --git a/src/ltltest/consterm.cc b/src/ltltest/consterm.cc
index ddf0b2e8d..94531c5c6 100644
--- a/src/ltltest/consterm.cc
+++ b/src/ltltest/consterm.cc
@@ -39,7 +39,7 @@ main(int argc, char **argv)
     syntax(argv[0]);
 
   spot::ltl::parse_error_list p1;
-  spot::ltl::formula* f1 = spot::ltl::parse(argv[1], p1);
+  spot::ltl::formula* f1 = spot::ltl::parse_ratexp(argv[1], p1);
 
   if (spot::ltl::format_parse_errors(std::cerr, argv[1], p1))
     return 2;
diff --git a/src/ltltest/consterm.test b/src/ltltest/consterm.test
index 864b489b4..9bab7b9b0 100755
--- a/src/ltltest/consterm.test
+++ b/src/ltltest/consterm.test
@@ -32,9 +32,8 @@ run 0 ../consterm '0'
 run 1 ../consterm '#e'
 run 1 ../consterm 'a*'
 run 1 ../consterm '0*'
-run 0 ../consterm '!#e'
-run 0 ../consterm '((a U b) + c)'
-run 1 ../consterm '((a U b) + #e)'
-run 0 ../consterm '((a U b) + #e) & e'
-run 1 ../consterm '((a U b) + #e) & #e'
-run 1 ../consterm '((a U b) + #e) & (a* + b)'
+run 0 ../consterm '((a ; b) + c)'
+run 1 ../consterm '((a ; b) + #e)'
+run 0 ../consterm '((a ; b) + #e) & e'
+run 1 ../consterm '((a ; b) + #e) & #e'
+run 1 ../consterm '((a ; b) + #e) & (a* + b)'
diff --git a/src/ltltest/equals.test b/src/ltltest/equals.test
index 15221b653..ea6983db2 100755
--- a/src/ltltest/equals.test
+++ b/src/ltltest/equals.test
@@ -70,17 +70,19 @@ run 0 ../equals 'a & b ^ c | d' 'd | c ^ b & a'
 run 0 ../equals 'FFG__GFF' 'F(F(G("__GFF")))'
 
 # Trivial simplifications
-run 0 ../equals '0*' '#e'
-run 0 ../equals '#e*' '#e'
-run 0 ../equals 'Exp**' 'Exp*'
+run 0 ../equals '{0*}<>->a' '{#e}<>->a'
+run 0 ../equals '{#e*}<>->a' '{#e}<>->a'
+run 0 ../equals '{Exp**}<>->a' '{Exp*}<>->a'
 run 0 ../equals 'FF(Exp)' 'F(Exp)'
 run 0 ../equals 'GG(Exp)' 'G(Exp)'
 run 0 ../equals 'F(0)' '0'
 run 0 ../equals 'G(0)' '0'
 run 0 ../equals 'F(1)' '1'
 run 0 ../equals 'G(1)' '1'
-run 0 ../equals 'F(#e)' '1'
-run 0 ../equals 'G(#e)' '1'
+run 0 ../equals 'F({#e}<>->1)' 'F({#e}<>->1)'
+run 0 ../equals 'G({#e}<>->1)' 'G({#e}<>->1)'
+run 0 ../equals 'F({1}<>->1)' '1'
+run 0 ../equals 'G({1}<>->1)' '1'
 run 0 ../equals '!1' '0'
 run 0 ../equals '!0' '1'
 run 0 ../equals '!!Exp' 'Exp'
@@ -105,12 +107,16 @@ run 0 ../equals GGx Gx
 run 0 ../equals GGGGGx Gx
 run 0 ../equals '!!x' x
 run 0 ../equals '!!!!!x' '!x'
-run 0 ../equals '#e;x' x
-run 0 ../equals 'x;#e' x
-run 0 ../equals '#e;x;#e;#e' x
-run 0 ../equals '#e;x;#e;x;#e' 'x;x'
-run 0 ../equals 'x;x;x;#e;x;x' 'x;x;x;x;x'
-run 0 ../equals 'x;0;x;x;x' '0'
-run 0 ../equals '0*' '#e'
-run 0 ../equals '#e*' '#e'
-run 0 ../equals 'x;x;FF(0)' '0'
+run 0 ../equals '{#e;x}<>->1' '{x}<>->1'
+run 0 ../equals '{x;#e}<>->1' '{x}<>-> 1'
+run 0 ../equals '{#e;x;#e;#e}<>->1' '{x}<>->1'
+run 0 ../equals '{#e;x;#e;x;#e}<>->1' '{x;x}<>->1'
+run 0 ../equals '{x;x;x;#e;x;x}<>->1' '{x;x;x;x;x}<>->1'
+run 0 ../equals '{x;0;x;x;x}<>->1' '0'
+run 0 ../equals '{x;0;x;x;x}[]->1' '1'
+run 0 ../equals '{0*;1}<>->x' 'x'
+run 0 ../equals '{#e*;1}<>->x' 'x'
+run 0 ../equals '{x;x}<>->FF(0)' '0'
+run 0 ../equals '{x;x}<>->GX(1)' '{x;x}<>->1'
+run 0 ../equals '{x;x}[]->GX(1)' '1'
+run 0 ../equals '{x;x}[]->FF(0)' '{x;x}[]->0'
diff --git a/src/ltltest/nenoform.test b/src/ltltest/nenoform.test
index f46682de8..0f6d1595c 100755
--- a/src/ltltest/nenoform.test
+++ b/src/ltltest/nenoform.test
@@ -68,6 +68,5 @@ run 0 ../nenoform '!(a U (!b U ((a & b & c) R d)))' \
 run 0 ../nenoform '!(GF a => FG b)' 'GFa & GF!b'
 
 # Rational operators
-run 0 ../nenoform '!(X((!Xa)*))' 'X!((X!a)*)'
-run 0 ../nenoform 'X((Xa)*)' 'X((Xa)*)'
-run 0 ../nenoform '!F!X!(GF(a);!FG(a);x)' 'GX!(GFa;GF!a;x)'
+run 0 ../nenoform '!X{a;b}<>->Fx' 'X{a;b}[]->G!x'
+run 0 ../nenoform '!F({a*}<>->{b*}<>->c)' 'G({a*}[]->{b*}[]->!c)'