Error with definition of #define

Projects Programming
3

This is the error:

sketch_nov04a\sketch_nov04a.ino: In function 'void setup()':

sketch_nov04a:7:23: error: expected primary-expression before '{' token

#define TIMEOUT_CHECK { if (millis() - timeout_start > timeout_ms) return ERROR_TIMEOUT; }

sketch_nov04a\sketch_nov04a.ino:13:33: note: in expansion of macro 'TIMEOUT_CHECK'

while (!Serial.available() && TIMEOUT_CHECK) {