diff --git a/include/ledmatrixdisplay.h b/include/ledmatrixdisplay.h
index d5878f71..b7ec5a3b 100644
--- a/include/ledmatrixdisplay.h
+++ b/include/ledmatrixdisplay.h
@@ -13,6 +13,6 @@ void refreshTheMatrixDisplay(bool nextPage = false);
 void DrawNumber(String strNum, uint8_t iDotPos = 0);
 uint8_t GetCharFromFont(char cChar);
 uint8_t GetCharWidth(char cChar);
-void ScrollLeft(uint8_t *buf, uint16_t cols, uint16_t rows);
+void ScrollLeft(uint8_t *buf, const uint16_t cols, const uint16_t rows);
 
 #endif
\ No newline at end of file
diff --git a/src/ledmatrixdisplay.cpp b/src/ledmatrixdisplay.cpp
index ffdad8c0..881f57fe 100644
--- a/src/ledmatrixdisplay.cpp
+++ b/src/ledmatrixdisplay.cpp
@@ -204,13 +204,14 @@ uint8_t GetCharWidth(char cChar) {
   return CharDescriptor.width;
 }
 
-void ScrollLeft(uint8_t *buf, uint16_t cols, uint16_t rows) {
+void ScrollLeft(uint8_t *buf, const uint16_t cols, const uint16_t rows) {
   uint32_t i, k, idx;
+  const uint32_t x = cols / 8;
 
   for (k = 0; k < rows; k++) {
     // scroll a line with x bytes one dot to the left
-    for (i = 0; i < cols / 8 - 1; ++i) {
-      idx = i + k * cols / 8;
+    for (i = 0; i < x - 1; ++i) {
+      idx = i + k * x;
       buf[idx] = (buf[idx] << 1) | ((buf[idx + 1] >> 7) & 1);
     }
     buf[idx + 1] <<= 1;