diff --git a/src/tipwin.cc b/src/tipwin.cc
index 6183ded..8dd6ebb 100644
--- a/src/tipwin.cc
+++ b/src/tipwin.cc
@@ -133,20 +133,18 @@ TipWinButton::TipWinButton(int x, int y, int w, int h, const char *l) :
     Fl_Button(x, y, w, h, l)
 {
    tipwin = my_tipwin();
-   mytooltip = dStrdup("empty");
 }
 
 TipWinButton::~TipWinButton(void)
 {
    tipwin->cancel(this); // cancel tooltip if shown
-   free(mytooltip);
 }
 
 int TipWinButton::handle(int e)
 {
    switch (e) {
    case FL_ENTER:
-      tipwin->value(mytooltip);
+      tipwin->value(mytooltip.c_str());
       tipwin->do_show(this);
       break;
    case FL_PUSH:            // push mouse
@@ -159,10 +157,9 @@ int TipWinButton::handle(int e)
    return (Fl_Button::handle(e));
 }
 
-void TipWinButton::set_tooltip(const char *s)
+void TipWinButton::set_tooltip(std::string s)
 {
-   free(mytooltip);
-   mytooltip = dStrdup(s);
+   mytooltip= std::move( s );
 }
 
 
@@ -210,20 +207,18 @@ TipWinInput::TipWinInput (int x, int y, int w, int h, const char *l) :
    Fl_Input(x,y,w,h,l)
 {
    tipwin = my_tipwin();
-   mytooltip = dStrdup("empty");
 }
 
-TipWinInput::~TipWinInput(void)
+TipWinInput::~TipWinInput()
 {
    tipwin->cancel(this); // cancel tooltip if shown
-   free(mytooltip);
 }
 
 int TipWinInput::handle(int e)
 {
    switch (e) {
    case FL_ENTER:
-      tipwin->value(mytooltip);
+      tipwin->value(mytooltip.c_str());
       tipwin->do_show(this);
       break;
    case FL_PUSH:            // push mouse
@@ -237,9 +232,8 @@ int TipWinInput::handle(int e)
    return (Fl_Input::handle(e));
 }
 
-void TipWinInput::set_tooltip(const char *s)
+void TipWinInput::set_tooltip(std::string s)
 {
-   free(mytooltip);
-   mytooltip = dStrdup(s);
+   mytooltip = std::move( s );
 }
 
diff --git a/src/tipwin.hh b/src/tipwin.hh
index bd9d444..771d9de 100644
--- a/src/tipwin.hh
+++ b/src/tipwin.hh
@@ -1,6 +1,8 @@
 #ifndef __TIPWIN_HH__
 #define __TIPWIN_HH__
 
+#include <string>
+
 #include <FL/Fl_Menu_Window.H>
 #include <FL/Fl_Button.H>
 #include <FL/Fl_Input.H>
@@ -33,14 +35,14 @@ extern TipWin *my_tipwin(void);
  * A Button sharing a custom tooltip window
  */
 class TipWinButton : public Fl_Button {
-   char *mytooltip;
+   std::string mytooltip= "empty";
    TipWin *tipwin;
  public:
    TipWinButton(int x, int y, int w, int h, const char *l = 0);
    ~TipWinButton();
    virtual int handle(int e);
 
-   void set_tooltip(const char *s);
+   void set_tooltip(std::string s);
 };
 
 /**
@@ -59,14 +61,14 @@ public:
  * An Input with custom tooltip window
  */
 class TipWinInput : public Fl_Input {
-   char *mytooltip;
+   std::string mytooltip= "empty";
    TipWin *tipwin;
 public:
    TipWinInput (int x, int y, int w, int h, const char* l=0);
-   ~TipWinInput(void);
+   ~TipWinInput();
    virtual int handle(int e);
 
-   void set_tooltip(const char *s);
+   void set_tooltip(std::string s);
 };