diff --git a/src/utils/Mouse.test.ts b/src/utils/Mouse.test.ts
index 4163263be..b96dd68ac 100644
--- a/src/utils/Mouse.test.ts
+++ b/src/utils/Mouse.test.ts
@@ -58,6 +58,6 @@ describe('getCoords', () => {
     assert.deepEqual(coords, [1, 1]);
     // Event are double the cols/rows
     coords = getCoords({ pageX: CHAR_WIDTH * 20, pageY: CHAR_HEIGHT * 20 }, document.createElement('div'), charMeasure, 1, 10, 10);
-    assert.deepEqual(coords, [11, 11], 'coordinates should never come back as larger than the terminal');
+    assert.deepEqual(coords, [10, 10], 'coordinates should never come back as larger than the terminal');
   });
 });
diff --git a/src/utils/Mouse.ts b/src/utils/Mouse.ts
index aef76d5ba..7bc39b7fc 100644
--- a/src/utils/Mouse.ts
+++ b/src/utils/Mouse.ts
@@ -53,8 +53,8 @@ export function getCoords(event: {pageX: number, pageY: number}, element: HTMLEl
   coords[1] = Math.ceil(coords[1] / Math.ceil(charMeasure.height * lineHeight));
 
   // Ensure coordinates are within the terminal viewport.
-  coords[0] = Math.min(Math.max(coords[0], 1), colCount + 1);
-  coords[1] = Math.min(Math.max(coords[1], 1), rowCount + 1);
+  coords[0] = Math.min(Math.max(coords[0], 1), colCount);
+  coords[1] = Math.min(Math.max(coords[1], 1), rowCount);
 
   return coords;
 }