diff --git a/firmware/modelibmmodelm.c b/firmware/modelibmmodelm.c
index 08a1c1a..6d7fa5f 100644
--- a/firmware/modelibmmodelm.c
+++ b/firmware/modelibmmodelm.c
@@ -270,7 +270,7 @@ uint8_t scankeys(uint8_t* reportBuffer, uint8_t* oldReportBuffer, uint8_t sizeOf
                     if (data & (1 << col)) {
                         key = pgm_read_byte(&keymatrix[row][col]);
                         modifier = pgm_read_byte(&modmatrix[row][col]);
-                        isghostkey = ghostmatrix[row] & (1 << col);
+                        isghostkey = (ghostmatrix[row] & (1 << col)) != 0;
                     } else {
                         key = KEY_Reserved;
                         modifier = MOD_NONE;
diff --git a/firmware/modelmayhem.c b/firmware/modelmayhem.c
index 6c177eb..fe6d16c 100644
--- a/firmware/modelmayhem.c
+++ b/firmware/modelmayhem.c
@@ -37,8 +37,6 @@
 #define LEDNUM      PIND3  ///< address of the num-lock LED
 #define LEDCAPS     PIND6  ///< address of the caps-lock LED
 #define LEDSCROLL   PIND7  ///< address of the scroll-lock LED
-#define LEDBACK1    PIND4  ///< address of the first backlight LED
-#define LEDBACK2    PIND5  ///< address of the second backlight LED
 
 uint8_t curmatrix[16];  ///< contains current state of the keyboard
 uint8_t oldmatrix[16];  ///< contains old state of the keyboard
@@ -272,7 +270,7 @@ uint8_t scankeys(uint8_t* reportBuffer, uint8_t* oldReportBuffer, uint8_t sizeOf
                     if (data & (1 << col)) {
                         key = pgm_read_byte(&keymatrix[row][col]);
                         modifier = pgm_read_byte(&modmatrix[row][col]);
-                        isghostkey = ghostmatrix[row] & (1 << col);
+                        isghostkey = (ghostmatrix[row] & (1 << col)) != 0;
                     } else {
                         key = KEY_Reserved;
                         modifier = MOD_NONE;
diff --git a/firmware/modelsuntype5.c b/firmware/modelsuntype5.c
index f82a772..bfb9b2a 100644
--- a/firmware/modelsuntype5.c
+++ b/firmware/modelsuntype5.c
@@ -94,7 +94,7 @@ void printMatrix(void) {
 }
 
 void setLeds(uint8_t LEDstate) {
-    if (LEDstate & LED_NUM) { // light up caps lock
+    if (LEDstate & LED_NUM) { // light up num lock
         PORTLEDS &= ~(1 << LEDNUM);
     } else {
         PORTLEDS |= (1 << LEDNUM);
@@ -104,7 +104,7 @@ void setLeds(uint8_t LEDstate) {
     } else {
         PORTLEDS |= (1 << LEDCAPS);
     }
-    if (LEDstate & LED_SCROLL) { // light up caps lock
+    if (LEDstate & LED_SCROLL) { // light up scroll lock
         PORTLEDS &= ~(1 << LEDSCROLL);
     } else {
         PORTLEDS |= (1 << LEDSCROLL);
@@ -240,9 +240,18 @@ uint8_t scankeys(uint8_t* reportBuffer, uint8_t* oldReportBuffer, uint8_t sizeOf
         debounce--;
     }
     if (debounce == 1) {
-        if (memcmp(oldmatrix, curmatrix, sizeof(curmatrix)) != 0) {
-            //printMatrix();
-            memcpy(oldmatrix, curmatrix, sizeof(curmatrix));
+        memset(ghostmatrix, 0, sizeof(ghostmatrix));
+        for (uint8_t i = 0; i < 21; i++) {
+            uint16_t keys = (~curmatrix[i]) & 0x1fff;
+            if (bitcount2(keys)) { // check if 2 or more keys are pressed
+                for (uint8_t j = i + 1; j < 22; j++) {
+                    uint16_t common_columns = keys & (~curmatrix[j]);
+                    if (bitcount2(common_columns)) { // 2 or more columns in common => ghostkeys
+                        ghostmatrix[i] |= common_columns;
+                        ghostmatrix[j] |= common_columns;
+                    }
+                }
+            }
         }
         // debounce counter expired, create report
         uint8_t reportIndex = 2; // reportBuffer[0] contains modifiers
@@ -255,7 +264,7 @@ uint8_t scankeys(uint8_t* reportBuffer, uint8_t* oldReportBuffer, uint8_t sizeOf
                     if (!(data & (1 << col))) {
                         key = pgm_read_byte(&keymatrix[row][col]);
                         modifier = pgm_read_byte(&modmatrix[row][col]);
-                        isghostkey = ghostmatrix[row] & (1 << col);
+                        isghostkey = (ghostmatrix[row] & (1 << col)) != 0;
                     } else {
                         key = KEY_Reserved;
                         modifier = MOD_NONE;