warning: inline variables are only available with -std=c++1z or -std=gnu++1z

Hello! do you have any idea how to avoid these warnings? Thanks!
In g++ parameters I already have -std=gnu++11 set.

C:…/avr-g++" -c -g -Os -Wall -Wextra -std=gnu++11
C:…TEST.ino:6:25: warning: inline variables are only available with -std=c++1z or -std=gnu++1z

Example code:

class A{
public:
inline static uint8_t z = 3;
};

void setup() {
Serial.begin(9600);
Serial.println(A::z);
}

void loop() {}

ops, please delete, the answer was obvious