diff --git a/src/common/buffer/BufferRange.ts b/src/common/buffer/BufferRange.ts
index 0b4902b1a..9091c68dc 100644
--- a/src/common/buffer/BufferRange.ts
+++ b/src/common/buffer/BufferRange.ts
@@ -7,7 +7,7 @@ import { IBufferRange } from 'xterm';
 
 export function getRangeLength(range: IBufferRange, cols: number): number {
   if (range.start.y === range.end.y) {
-    return range.end.x - range.start.x;
+    return range.end.x - range.start.x + 1;
   }
   if (range.start.y > range.end.y) {
     throw new Error(`Buffer range end (${range.end.x}, ${range.end.y}) cannot be before start (${range.start.x}, ${range.start.y})`);