Programming :: G++ Warning - Deprecated Conversion From String Constant To 'char*'

My problem is that the warning keeps apperaing when I run g++ compilation.

Say, I have a system runtime function with header (imaginary)sysruntime.h: void printfunction(char *line);

Then in my .cpp file, I will include the above header #include <sysruntime.h>

Then, I do the below:
Line12: char *linetoprint = "Print this line";
Line13: printfunction(linetoprint);

But, I will get the warning message "Line12: deprecated conversion from string constant to 'char*'". (Even though it compiles)

My question is how should I declare my char* so that I wont get this warning message, and can still run printfunction(char* line) correctly?