diff --git a/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1CommandsLib.c b/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1CommandsLib.c
index d26d08f95c..b45e9a33f3 100644
--- a/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1CommandsLib.c
+++ b/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1CommandsLib.c
@@ -205,7 +205,7 @@ EditorClearLine (
         //
         // if CHAR_NULL is still at position LastCol, it will cause first line error
         //
-        Line[(LastCol % (ARRAY_SIZE (Line) - 1)) - 1] = CHAR_NULL;
+        Line[(LastCol - 1) % (ARRAY_SIZE (Line) - 1)] = CHAR_NULL;
       } else {
         Line[LastCol % (ARRAY_SIZE (Line) - 1)] = CHAR_NULL;
       }