diff --git a/ext/bg/data/options-schema.json b/ext/bg/data/options-schema.json
index 71d5e7db..2e324984 100644
--- a/ext/bg/data/options-schema.json
+++ b/ext/bg/data/options-schema.json
@@ -343,7 +343,7 @@
                                         "default": [
                                             {
                                                 "include": "shift",
-                                                "exclude": "",
+                                                "exclude": "mouse0",
                                                 "types": {
                                                     "mouse": true,
                                                     "touch": false,
diff --git a/ext/bg/js/options.js b/ext/bg/js/options.js
index 5b61b870..f9571ec2 100644
--- a/ext/bg/js/options.js
+++ b/ext/bg/js/options.js
@@ -550,7 +550,7 @@ class OptionsUtil {
             }
             scanningInputs.push({
                 include: modifierInput,
-                exclude: '',
+                exclude: 'mouse0',
                 types: {mouse: true, touch: false, pen: false},
                 options: createInputDefaultOptions()
             });
diff --git a/ext/mixed/js/document-util.js b/ext/mixed/js/document-util.js
index d448fc3c..90add8f9 100644
--- a/ext/mixed/js/document-util.js
+++ b/ext/mixed/js/document-util.js
@@ -169,16 +169,6 @@ class DocumentUtil {
         }
     }
 
-    static isMouseButtonDown(mouseEvent, button) {
-        const mouseEventButtons = mouseEvent.buttons;
-        switch (button) {
-            case 'primary': return (mouseEventButtons & 0x1) !== 0x0;
-            case 'secondary': return (mouseEventButtons & 0x2) !== 0x0;
-            case 'auxiliary': return (mouseEventButtons & 0x4) !== 0x0;
-            default: return false;
-        }
-    }
-
     static getActiveModifiers(event) {
         const modifiers = new Set();
         if (event.altKey) { modifiers.add('alt'); }
diff --git a/ext/mixed/js/text-scanner.js b/ext/mixed/js/text-scanner.js
index f38ca1de..aacc683a 100644
--- a/ext/mixed/js/text-scanner.js
+++ b/ext/mixed/js/text-scanner.js
@@ -267,10 +267,6 @@ class TextScanner extends EventDispatcher {
     _onMouseMove(e) {
         this._scanTimerClear();
 
-        if (DocumentUtil.isMouseButtonDown(e, 'primary')) {
-            return;
-        }
-
         const inputInfo = this._getMatchingInputGroupFromEvent(e, 'mouse');
         if (inputInfo === null) { return; }
 
@@ -286,7 +282,7 @@ class TextScanner extends EventDispatcher {
             return false;
         }
 
-        if (DocumentUtil.isMouseButtonDown(e, 'primary')) {
+        if (e.button === 0) { // Primary
             this._scanTimerClear();
             this.clearSelection(false);
         }
diff --git a/test/test-options-util.js b/test/test-options-util.js
index 67dc57b7..3c6e8733 100644
--- a/test/test-options-util.js
+++ b/test/test-options-util.js
@@ -319,7 +319,7 @@ function createProfileOptionsUpdatedTestData1() {
             inputs: [
                 {
                     include: 'shift',
-                    exclude: '',
+                    exclude: 'mouse0',
                     types: {
                         mouse: true,
                         touch: false,