diff --git a/src/cli.h b/src/cli.h
index 718e976..74f3fee 100644
--- a/src/cli.h
+++ b/src/cli.h
@@ -76,6 +76,7 @@ private:
 class Command {
 public:
     Command (CommandInterpreter *cli, ProcessController *pcm, const char **commands) ;
+    virtual ~Command() { }
 
     virtual void check (std::string root, CommandVec &result) ;          // check if string matches command exactly
     virtual void check_abbreviation (std::string root, CommandVec &result) ;          // check if string matches command abbreviation
@@ -114,6 +115,7 @@ private:
 
 class ControlCommand : public Command {
 public:
+    virtual ~ControlCommand() { }
     ControlCommand(CommandInterpreter *cli, ProcessController *pcm) ;
     void execute (std::string root, std::string tail) ;
     bool is_dangerous (std::string cmd) ;
@@ -124,6 +126,7 @@ private:
 
 class DebuggerCommand : public Command {
 public:
+    virtual ~DebuggerCommand() { }
     DebuggerCommand(CommandInterpreter *cli, ProcessController *pcm) ;
     void execute (std::string root, std::string tail) ;
     void  complete (std::string root, std::string tail, int ch, std::vector<std::string> &result) ;
@@ -134,6 +137,7 @@ private:
 
 class BreakpointCommand : public Command {
 public:
+    virtual ~BreakpointCommand() { }
     BreakpointCommand(CommandInterpreter *cli, ProcessController *pcm) ;
     void execute (std::string root, std::string tail) ;
     void  complete (std::string root, std::string tail, int ch, std::vector<std::string> &result) ;
@@ -407,7 +411,7 @@ private:
     ProcessController *pcm ;
     PStream &os ;
     std::vector<Command*> commands ;
-    sighandler_t oldint ;
+    void (*oldint)(int);
     bool program_running ;
     std::istream *instream ;            // current input stream (NULL means keyboard)
 
diff --git a/src/readline.h b/src/readline.h
index aa9d3f7..51c9205 100644
--- a/src/readline.h
+++ b/src/readline.h
@@ -29,6 +29,7 @@ author: James Strother <jims@pathscale.com>
 
 class Completor {
 public:
+   virtual ~Completor() { }
    virtual std::string complete (std::string text, int ch) = 0;
    virtual void list_matches() = 0;
    virtual unsigned num_matches() = 0;