diff --git a/src/windows.c b/src/windows.c
index bea75e26..53090eaf 100644
--- a/src/windows.c
+++ b/src/windows.c
@@ -1319,7 +1319,7 @@ void Print_counter(short x,short y,const char * str,byte text_color,byte backgro
 /// center the lines, but the carriage returns have to be explicit.
 /// The function will clip the message in case of problem.
 /// @return 1 if user pressed OK, 0 if CANCEL
-byte Confirmation_box(char * message)
+byte Confirmation_box(const char * message)
 {
   short clicked_button;
   word  window_width = 120;
@@ -1398,7 +1398,7 @@ byte Confirmation_box(char * message)
 
 
 /// Window that allows you to enter a single value
-int Requester_window(char* message, int initial_value)
+int Requester_window(const char* message, int initial_value)
 {
   short clicked_button = 0;
   word window_width;
@@ -1441,7 +1441,7 @@ int Requester_window(char* message, int initial_value)
 
 
 /// Window that show a warning message and wait for a click on the OK button
-void Warning_message(char * message)
+void Warning_message(const char * message)
 {
   short clicked_button;
   word  window_width;
diff --git a/src/windows.h b/src/windows.h
index fb950cd8..e7fccefc 100644
--- a/src/windows.h
+++ b/src/windows.h
@@ -77,11 +77,11 @@ void Print_coordinates(void);
 void Print_filename(void);
 void Print_counter(short x,short y,const char * str,byte text_color,byte background_color);
 
-byte Confirmation_box(char * message);
-void Warning_message(char * message);
+byte Confirmation_box(const char * message);
+void Warning_message(const char * message);
 void Warning_with_format(const char * message, ...);
 void Verbose_message(const char * caption, const char * message);
-int Requester_window(char* message, int initial_value);
+int Requester_window(const char* message, int initial_value);
 
 void Display_image_limits(void);
 void Display_all_screen(void);