missed a static declaration

counter~.c

@@ -18,7 +18,7 @@ typedef struct _counter
 } t_counter;
 
 static void *counter_new(t_symbol *s, int argc, t_atom *argv);
-t_int *counter_perform(t_int *w);
+static t_int *counter_perform(t_int *w);
 static void counter_dsp(t_counter *x, t_signal **sp);
 static void counter_setnext(t_counter *x, t_floatarg val);
 static void counter_direction(t_counter *x, t_floatarg d);