diff --git a/OLEDDisplayUi.cpp b/OLEDDisplayUi.cpp
index 163c2e906935eb90475e5ad107ff919a18a40b50..cea3bb5d37aafb289fb1acb1065dd5565a95acf1 100644
--- a/OLEDDisplayUi.cpp
+++ b/OLEDDisplayUi.cpp
@@ -90,10 +90,10 @@ void OLEDDisplayUi::setIndicatorPosition(IndicatorPosition pos) {
 void OLEDDisplayUi::setIndicatorDirection(IndicatorDirection dir) {
   this->indicatorDirection = dir;
 }
-void OLEDDisplayUi::setActiveSymbol(const char* symbol) {
+void OLEDDisplayUi::setActiveSymbol(const unsigned char* symbol) {
   this->activeSymbol = symbol;
 }
-void OLEDDisplayUi::setInactiveSymbol(const char* symbol) {
+void OLEDDisplayUi::setInactiveSymbol(const unsigned char* symbol) {
   this->inactiveSymbol = symbol;
 }
 
diff --git a/OLEDDisplayUi.h b/OLEDDisplayUi.h
index 617346a3a2ede21c9f09a19a279aa89d4cbe8387..ac2d9ed3c5266a1348550d5616c72a2f72f36f40 100644
--- a/OLEDDisplayUi.h
+++ b/OLEDDisplayUi.h
@@ -61,11 +61,11 @@ enum FrameState {
 };
 
 
-const char ANIMATION_activeSymbol[] PROGMEM = {
+const unsigned char ANIMATION_activeSymbol[] PROGMEM = {
   0x00, 0x18, 0x3c, 0x7e, 0x7e, 0x3c, 0x18, 0x00
 };
 
-const char ANIMATION_inactiveSymbol[] PROGMEM = {
+const unsigned char ANIMATION_inactiveSymbol[] PROGMEM = {
   0x00, 0x0, 0x0, 0x18, 0x18, 0x0, 0x0, 0x00
 };
 
@@ -106,8 +106,8 @@ class OLEDDisplayUi {
     IndicatorPosition   indicatorPosition         = BOTTOM;
     IndicatorDirection  indicatorDirection        = LEFT_RIGHT;
 
-    const char*         activeSymbol              = ANIMATION_activeSymbol;
-    const char*         inactiveSymbol            = ANIMATION_inactiveSymbol;
+    const unsigned char*         activeSymbol              = ANIMATION_activeSymbol;
+    const unsigned char*         inactiveSymbol            = ANIMATION_inactiveSymbol;
 
     bool                shouldDrawIndicators      = true;
 
@@ -240,12 +240,12 @@ class OLEDDisplayUi {
     /**
      * Set the symbol to indicate an active frame in the indicator bar.
      */
-    void setActiveSymbol(const char* symbol);
+    void setActiveSymbol(const unsigned char* symbol);
 
     /**
      * Set the symbol to indicate an inactive frame in the indicator bar.
      */
-    void setInactiveSymbol(const char* symbol);
+    void setInactiveSymbol(const unsigned char* symbol);
 
 
     // Frame settings