diff --git a/ssd1306.h b/ssd1306.h
--- a/ssd1306.h
+++ b/ssd1306.h
@@ -50,5 +50,6 @@ unsigned long ssd1306_DrawPoint(Pos_t x,
 void ssd1306_block_write(void);
 void ssd1306_DrawChar(char ascii, unsigned char row, unsigned char xPos);
 void ssd1306_DrawString(const char *dataPtr, unsigned char row, unsigned char xPos);
+void ssd1306_test();
 
 #endif