diff --git a/latan/MathCompiler.cpp b/latan/MathCompiler.cpp
index 927adc4..e6d3110 100644
--- a/latan/MathCompiler.cpp
+++ b/latan/MathCompiler.cpp
@@ -85,6 +85,9 @@ MathParserState::~MathParserState(void)
 #define CODE_WIDTH 6
 #define CODE_MOD   setw(CODE_WIDTH) << left
 
+Instruction::~Instruction(void)
+{}
+
 void Instruction::Print(std::ostream &out) const
 {
     out << CODE_MOD << "<null>" << CODE_MOD << "ABSTRACT INSTRUCTION!";
diff --git a/latan/MathCompiler.hpp b/latan/MathCompiler.hpp
index 8d2838d..cb02806 100644
--- a/latan/MathCompiler.hpp
+++ b/latan/MathCompiler.hpp
@@ -63,7 +63,7 @@ private:
 };
 
 /******************************************************************************
- *                          Virtual machine classes                           *
+ *                       Virtual machine code classes                         *
  ******************************************************************************/
 typedef std::map<std::string,double> VarTable;
 
@@ -71,7 +71,7 @@ typedef std::map<std::string,double> VarTable;
 class Instruction
 {
 public:
-    virtual ~Instruction() {};
+    virtual ~Instruction();
     // instruction execution
     virtual void operator()(std::stack<double>& dstack, VarTable& vtable) = 0;
     friend std::ostream& operator<<(std::ostream& out, const Instruction& ins);