diff --git a/ext/bg/js/options.js b/ext/bg/js/options.js
index 8c9e49e1..c3321012 100644
--- a/ext/bg/js/options.js
+++ b/ext/bg/js/options.js
@@ -27,7 +27,7 @@ function formRead() {
 
         optionsNew.general.showGuide = $('#show-usage-guide').prop('checked');
         optionsNew.general.audioSource = $('#audio-playback-source').val();
-        optionsNew.general.audioVolume = $('#audio-playback-volume').val();
+        optionsNew.general.audioVolume = parseFloat($('#audio-playback-volume').val());
         optionsNew.general.groupResults = $('#group-terms-results').prop('checked');
         optionsNew.general.debugInfo = $('#show-debug-info').prop('checked');
         optionsNew.general.showAdvanced = $('#show-advanced-options').prop('checked');
@@ -36,12 +36,12 @@ function formRead() {
         optionsNew.general.popupHeight = parseInt($('#popup-height').val(), 10);
         optionsNew.general.popupOffset = parseInt($('#popup-offset').val(), 10);
 
-        optionsNew.scanning.requireShift = $('#hold-shift-to-scan').prop('checked');
         optionsNew.scanning.middleMouse = $('#middle-mouse-button-scan').prop('checked');
         optionsNew.scanning.selectText = $('#select-matched-text').prop('checked');
         optionsNew.scanning.alphanumeric = $('#search-alphanumeric').prop('checked');
         optionsNew.scanning.delay = parseInt($('#scan-delay').val(), 10);
         optionsNew.scanning.length = parseInt($('#scan-length').val(), 10);
+        optionsNew.scanning.modifier = $('#scan-modifier-key').val();
 
         optionsNew.anki.enable = $('#anki-enable').prop('checked');
         optionsNew.anki.tags = $('#card-tags').val().split(/[,; ]+/);
@@ -132,12 +132,12 @@ $(document).ready(() => {
         $('#popup-height').val(options.general.popupHeight);
         $('#popup-offset').val(options.general.popupOffset);
 
-        $('#hold-shift-to-scan').prop('checked', options.scanning.requireShift);
         $('#middle-mouse-button-scan').prop('checked', options.scanning.middleMouse);
         $('#select-matched-text').prop('checked', options.scanning.selectText);
         $('#search-alphanumeric').prop('checked', options.scanning.alphanumeric);
         $('#scan-delay').val(options.scanning.delay);
         $('#scan-length').val(options.scanning.length);
+        $('#scan-modifier-key').val(options.scanning.modifier);
 
         $('#dict-purge').click(onDictionaryPurge);
         $('#dict-importer a').click(onDictionarySetUrl);
diff --git a/ext/bg/js/util.js b/ext/bg/js/util.js
index 413fbaca..75833871 100644
--- a/ext/bg/js/util.js
+++ b/ext/bg/js/util.js
@@ -108,12 +108,12 @@ function optionsSetDefaults(options) {
         },
 
         scanning: {
-            requireShift: true,
             middleMouse: true,
             selectText: true,
             alphanumeric: true,
             delay: 15,
-            length: 10
+            length: 10,
+            modifier: 'shift'
         },
 
         dictionaries: {},
@@ -149,10 +149,10 @@ function optionsSetDefaults(options) {
 
 function optionsVersion(options) {
     const fixups = [
-        () => { },
-        () => { },
-        () => { },
-        () => { },
+        () => {},
+        () => {},
+        () => {},
+        () => {},
         () => {
             if (options.general.audioPlayback) {
                 options.general.audioSource = 'jpod101';
@@ -162,6 +162,13 @@ function optionsVersion(options) {
         },
         () => {
             options.general.showGuide = false;
+        },
+        () => {
+            if (options.scanning.requireShift) {
+                options.scanning.modifier = 'shift';
+            } else {
+                options.scanning.modifier = 'none';
+            }
         }
     ];
 
diff --git a/ext/bg/options.html b/ext/bg/options.html
index e36e0511..6a359f5e 100644
--- a/ext/bg/options.html
+++ b/ext/bg/options.html
@@ -82,10 +82,6 @@
                     <label><input type="checkbox" id="middle-mouse-button-scan"> Middle mouse button scans</label>
                 </div>
 
-                <div class="checkbox">
-                    <label><input type="checkbox" id="hold-shift-to-scan"> Hold <kbd>Shift</kbd> to scan</label>
-                </div>
-
                 <div class="checkbox">
                     <label><input type="checkbox" id="select-matched-text"> Select matched text</label>
                 </div>
@@ -103,6 +99,16 @@
                     <label for="scan-length">Scan length (in characters)</label>
                     <input type="number" min="1" id="scan-length" class="form-control">
                 </div>
+
+                <div class="form-group">
+                    <label for="scan-modifier-key">Scan modifier key</label>
+                    <select class="form-control" id="scan-modifier-key">
+                        <option value="none">None</option>
+                        <option value="alt">Alt</option>
+                        <option value="ctrl">Ctrl</option>
+                        <option value="shift">Shift</option>
+                    </select>
+                </div>
             </div>
 
             <div>
diff --git a/ext/fg/js/driver.js b/ext/fg/js/driver.js
index bdcc01b3..b0cc4613 100644
--- a/ext/fg/js/driver.js
+++ b/ext/fg/js/driver.js
@@ -70,15 +70,22 @@ window.driver = new class {
             return;
         }
 
-        if (this.options.scanning.requireShift && !e.shiftKey && !(this.mouseDownMiddle && this.options.scanning.middleMouse)) {
+        const mouseScan = this.mouseDownMiddle && this.options.scanning.middleMouse;
+        const keyScan =
+            this.options.scanning.modifier === 'alt' && e.altKey ||
+            this.options.scanning.modifier === 'ctrl' && e.ctrlKey ||
+            this.options.scanning.modifier === 'shift' && e.shiftKey ||
+            this.options.scanning.modifier === 'none';
+
+        if (!keyScan && !mouseScan) {
             return;
         }
 
         const searchFunc = () => this.searchAt(this.lastMousePos);
-        if (this.options.scanning.requireShift) {
-            searchFunc();
-        } else {
+        if (this.options.scanning.modifier === 'none') {
             this.popupTimerSet(searchFunc);
+        } else {
+            searchFunc();
         }
     }
 
@@ -232,7 +239,7 @@ window.driver = new class {
 
     handleError(error, textSource) {
         if (window.orphaned) {
-            if (textSource && this.options.scanning.requireShift) {
+            if (textSource && this.options.scanning.modifier !== 'none') {
                 this.popup.showOrphaned(textSource.getRect(), this.options);
             }
         } else {