diff --git a/include/sound4calc.h b/include/sound4calc.h
index d9b5ebe..d6903b4 100644
--- a/include/sound4calc.h
+++ b/include/sound4calc.h
@@ -4,7 +4,7 @@
 
 struct Wave
 {
-    char* signal;
+    char signal[25];
     unsigned short length;
 };
 
@@ -15,7 +15,6 @@ extern struct Note
     unsigned int freq;
 } note;
 
-
 void CallSequence();
 void CallNote();
 void PutPinState(char level);
diff --git a/src/main.c b/src/main.c
index d0ed060..e33a9db 100644
--- a/src/main.c
+++ b/src/main.c
@@ -12,6 +12,10 @@ int main(void)
     unsigned short place = 0;
   //unsigned int i=0;
 
+  note.freq = 440;
+  note.wave.signal[0] = 0;
+  note.duration = 2000;
+
     InitPorts();
 
     while(1)
@@ -37,8 +41,8 @@ int main(void)
             case KEY_UP : note.freq+=10; break;
             case KEY_DOWN : note.freq-=10; break;
 
-            case KEY_F5 : *(note.wave.signal+place++) = '_'; break;
-            case KEY_F6 : *(note.wave.signal+place++) = '-'; break;
+            case KEY_F5 : *(note.wave.signal+place++) = '_'; *(note.wave.signal+place) = 0; break;
+            case KEY_F6 : *(note.wave.signal+place++) = '-'; *(note.wave.signal+place) = 0; break;
             case KEY_DEL : place=(place>0 ? place - 1 : 0); *(note.wave.signal+place) = 0; break;
 
             case KEY_F1 : CallNote(); break;