diff --git a/examples/SSD1306UiDemo/images.h b/examples/SSD1306UiDemo/images.h
index ccc778eb149b54bf97d130b5446357a6e808e246..662bd1f8c75702ab2e777e41f8c65924668614a6 100644
--- a/examples/SSD1306UiDemo/images.h
+++ b/examples/SSD1306UiDemo/images.h
@@ -27,7 +27,7 @@ const unsigned char WiFi_Logo_bits[] PROGMEM = {
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
   };
 
-const char activeSymbol[] PROGMEM = {
+const unsigned char activeSymbol[] PROGMEM = {
     B00000000,
     B00000000,
     B00011000,
@@ -38,7 +38,7 @@ const char activeSymbol[] PROGMEM = {
     B00011000
 };
 
-const char inactiveSymbol[] PROGMEM = {
+const unsigned char inactiveSymbol[] PROGMEM = {
     B00000000,
     B00000000,
     B00000000,