diff --git a/src/ltlast/atomic_prop.hh b/src/ltlast/atomic_prop.hh
index 6262f2245..c7714e8a5 100644
--- a/src/ltlast/atomic_prop.hh
+++ b/src/ltlast/atomic_prop.hh
@@ -38,7 +38,7 @@ namespace spot
 
     /// \ingroup ltl_ast
     /// \brief Atomic propositions.
-    class SPOT_API atomic_prop : public formula
+    class SPOT_API atomic_prop final : public formula
     {
     public:
       /// Build an atomic proposition with name \a name in
@@ -46,7 +46,7 @@ namespace spot
       static const atomic_prop*
       instance(const std::string& name, environment& env);
 
-      virtual void accept(visitor& visitor) const;
+      virtual void accept(visitor& visitor) const override;
 
       /// Get the name of the atomic proposition.
       const std::string& name() const
@@ -61,7 +61,7 @@ namespace spot
       }
 
       /// Return a canonic representation of the atomic proposition
-      virtual std::string dump() const;
+      virtual std::string dump() const override;
 
       /// Number of instantiated atomic propositions.  For debugging.
       static unsigned instance_count();
diff --git a/src/ltlast/binop.hh b/src/ltlast/binop.hh
index ccecef3ab..4fbd74aa7 100644
--- a/src/ltlast/binop.hh
+++ b/src/ltlast/binop.hh
@@ -40,7 +40,7 @@ namespace spot
 
     /// \ingroup ltl_ast
     /// \brief Binary operator.
-    class SPOT_API binop : public formula
+    class SPOT_API binop final: public formula
     {
     public:
       /// Different kinds of binary opertaors
@@ -110,7 +110,7 @@ namespace spot
 				     const formula* first,
 				     const formula* second);
 
-      virtual void accept(visitor& v) const;
+      virtual void accept(visitor& v) const override;
 
       /// Get the first operand.
       const formula* first() const
@@ -134,7 +134,7 @@ namespace spot
       const char* op_name() const;
 
       /// Return a canonic representation of the atomic proposition
-      virtual std::string dump() const;
+      virtual std::string dump() const override;
 
       /// Number of instantiated binary operators.  For debugging.
       static unsigned instance_count();
diff --git a/src/ltlast/bunop.hh b/src/ltlast/bunop.hh
index d3b157c1b..30205d500 100644
--- a/src/ltlast/bunop.hh
+++ b/src/ltlast/bunop.hh
@@ -35,7 +35,7 @@ namespace spot
 
     /// \ingroup ltl_ast
     /// \brief Bounded unary operator.
-    class SPOT_API bunop : public formula
+    class SPOT_API bunop final : public formula
     {
     public:
       enum type { Star };
@@ -85,7 +85,7 @@ namespace spot
 					unsigned min = 0,
 					unsigned max = unbounded);
 
-      virtual void accept(visitor& v) const;
+      virtual void accept(visitor& v) const override;
 
       /// Get the sole operand of this operator.
       const formula* child() const
@@ -120,7 +120,7 @@ namespace spot
       const char* op_name() const;
 
       /// Return a canonic representation of operation.
-      virtual std::string dump() const;
+      virtual std::string dump() const override;
 
       /// Number of instantiated unary operators.  For debugging.
       static unsigned instance_count();
diff --git a/src/ltlast/constant.hh b/src/ltlast/constant.hh
index 96d018c70..4081fd7f5 100644
--- a/src/ltlast/constant.hh
+++ b/src/ltlast/constant.hh
@@ -32,11 +32,11 @@ namespace spot
 
     /// \ingroup ltl_ast
     /// \brief A constant (True or False)
-    class SPOT_API constant : public formula
+    class SPOT_API constant final : public formula
     {
     public:
       enum type { False, True, EmptyWord };
-      virtual void accept(visitor& v) const;
+      virtual void accept(visitor& v) const override;
 
       /// Return the value of the constant.
       type val() const
@@ -47,7 +47,7 @@ namespace spot
       /// Return the value of the constant as a string.
       const char* val_name() const;
 
-      virtual std::string dump() const;
+      virtual std::string dump() const override;
 
       /// Get the sole instance of spot::ltl::constant::constant(True).
       static constant* true_instance() { return &true_instance_; }
diff --git a/src/ltlast/unop.hh b/src/ltlast/unop.hh
index 6b56966d3..d8b51a918 100644
--- a/src/ltlast/unop.hh
+++ b/src/ltlast/unop.hh
@@ -36,7 +36,7 @@ namespace spot
 
     /// \ingroup ltl_ast
     /// \brief Unary operators.
-    class SPOT_API unop : public formula
+    class SPOT_API unop final : public formula
     {
     public:
       enum type {
@@ -87,7 +87,7 @@ namespace spot
       /// handle this one as well.
       static const formula* instance(type op, const formula* child);
 
-      virtual void accept(visitor& v) const;
+      virtual void accept(visitor& v) const override;
 
       /// Get the sole operand of this operator.
       const formula* child() const
@@ -105,7 +105,7 @@ namespace spot
       const char* op_name() const;
 
       /// Return a canonic representation of the atomic proposition
-      virtual std::string dump() const;
+      virtual std::string dump() const override;
 
       /// Number of instantiated unary operators.  For debugging.
       static unsigned instance_count();
diff --git a/src/misc/common.hh b/src/misc/common.hh
index 08b336cb3..76c2a1b98 100644
--- a/src/misc/common.hh
+++ b/src/misc/common.hh
@@ -78,8 +78,11 @@
 
 // Swig 2.0 does not understand '= delete'.  This already
 // works with the development version of Swig 3.
+// Swig 3.0.2 still does not understand 'final' when used
+// at class definition.
 #ifdef SWIG
   #define SPOT_DELETED
+  #define final
 #else
   #define SPOT_DELETED = delete
 #endif