diff --git a/ayab/plugins/ayab_plugin/ayab_control.py b/ayab/plugins/ayab_plugin/ayab_control.py
index 8639c1f1..84cd0197 100644
--- a/ayab/plugins/ayab_plugin/ayab_control.py
+++ b/ayab/plugins/ayab_plugin/ayab_control.py
@@ -443,7 +443,7 @@ def __cnfLine(self, lineNumber):
                     lineNumber = lineNumber % lenImgExpanded
 
                 # calculate imgRow
-                imgRow = int(lineNumber / 2) + self.__startLine
+                imgRow = (int(lineNumber / 2) + self.__startLine) % imgHeight
 
                 # 0 0 1 1 2 2 3 3 4 4 .. (imgRow)
                 # 0 1 2 3 4 5 6 7 8 9 .. (lineNumber)
@@ -464,6 +464,8 @@ def __cnfLine(self, lineNumber):
                 else:
                     indexToSend += lineNumber
 
+                indexToSend = indexToSend % lenImgExpanded
+
                 # Decide whether to send lastLine Flag
                 if (imgRow == imgHeight - 1) \
                         and (lineNumber % 4 == 1 or lineNumber % 4 == 3):