diff --git a/dev/tools/gen_keycodes/data/web_logical_location_mapping.json b/dev/tools/gen_keycodes/data/web_logical_location_mapping.json
index c5b19daf191..dd06fd11798 100644
--- a/dev/tools/gen_keycodes/data/web_logical_location_mapping.json
+++ b/dev/tools/gen_keycodes/data/web_logical_location_mapping.json
@@ -26,8 +26,8 @@
   "-": ["Minus", null, null, "NumpadSubtract"],
   "+": ["Add", null, null, "NumpadAdd"],
   "Enter": ["Enter", null, null, "NumpadEnter"],
-  "Shift": [null, "ShiftLeft", "ShiftRight", null],
-  "Control": [null, "ControlLeft", "ControlRight", null],
-  "Alt": [null, "AltLeft", "AltRight", null],
-  "Meta": [null, "MetaLeft", "MetaRight", null]
+  "Shift": ["ShiftLeft", "ShiftLeft", "ShiftRight", null],
+  "Control": ["ControlLeft", "ControlLeft", "ControlRight", null],
+  "Alt": ["AltLeft", "AltLeft", "AltRight", null],
+  "Meta": ["MetaLeft", "MetaLeft", "MetaRight", null]
 }
diff --git a/packages/flutter/lib/src/services/keyboard_maps.dart b/packages/flutter/lib/src/services/keyboard_maps.dart
index 3375b30b77e..89453719af7 100644
--- a/packages/flutter/lib/src/services/keyboard_maps.dart
+++ b/packages/flutter/lib/src/services/keyboard_maps.dart
@@ -2760,22 +2760,22 @@ const Map<String, List<LogicalKeyboardKey?>> kWebLocationMap = <String, List<Log
   '7': <LogicalKeyboardKey?>[LogicalKeyboardKey.digit7, null, null, LogicalKeyboardKey.numpad7],
   '8': <LogicalKeyboardKey?>[LogicalKeyboardKey.digit8, null, null, LogicalKeyboardKey.numpad8],
   '9': <LogicalKeyboardKey?>[LogicalKeyboardKey.digit9, null, null, LogicalKeyboardKey.numpad9],
-  'Alt': <LogicalKeyboardKey?>[null, LogicalKeyboardKey.altLeft, LogicalKeyboardKey.altRight, null],
+  'Alt': <LogicalKeyboardKey?>[LogicalKeyboardKey.altLeft, LogicalKeyboardKey.altLeft, LogicalKeyboardKey.altRight, null],
   'ArrowDown': <LogicalKeyboardKey?>[LogicalKeyboardKey.arrowDown, null, null, LogicalKeyboardKey.numpad2],
   'ArrowLeft': <LogicalKeyboardKey?>[LogicalKeyboardKey.arrowLeft, null, null, LogicalKeyboardKey.numpad4],
   'ArrowRight': <LogicalKeyboardKey?>[LogicalKeyboardKey.arrowRight, null, null, LogicalKeyboardKey.numpad6],
   'ArrowUp': <LogicalKeyboardKey?>[LogicalKeyboardKey.arrowUp, null, null, LogicalKeyboardKey.numpad8],
   'Clear': <LogicalKeyboardKey?>[LogicalKeyboardKey.clear, null, null, LogicalKeyboardKey.numpad5],
-  'Control': <LogicalKeyboardKey?>[null, LogicalKeyboardKey.controlLeft, LogicalKeyboardKey.controlRight, null],
+  'Control': <LogicalKeyboardKey?>[LogicalKeyboardKey.controlLeft, LogicalKeyboardKey.controlLeft, LogicalKeyboardKey.controlRight, null],
   'Delete': <LogicalKeyboardKey?>[LogicalKeyboardKey.delete, null, null, LogicalKeyboardKey.numpadDecimal],
   'End': <LogicalKeyboardKey?>[LogicalKeyboardKey.end, null, null, LogicalKeyboardKey.numpad1],
   'Enter': <LogicalKeyboardKey?>[LogicalKeyboardKey.enter, null, null, LogicalKeyboardKey.numpadEnter],
   'Home': <LogicalKeyboardKey?>[LogicalKeyboardKey.home, null, null, LogicalKeyboardKey.numpad7],
   'Insert': <LogicalKeyboardKey?>[LogicalKeyboardKey.insert, null, null, LogicalKeyboardKey.numpad0],
-  'Meta': <LogicalKeyboardKey?>[null, LogicalKeyboardKey.metaLeft, LogicalKeyboardKey.metaRight, null],
+  'Meta': <LogicalKeyboardKey?>[LogicalKeyboardKey.metaLeft, LogicalKeyboardKey.metaLeft, LogicalKeyboardKey.metaRight, null],
   'PageDown': <LogicalKeyboardKey?>[LogicalKeyboardKey.pageDown, null, null, LogicalKeyboardKey.numpad3],
   'PageUp': <LogicalKeyboardKey?>[LogicalKeyboardKey.pageUp, null, null, LogicalKeyboardKey.numpad9],
-  'Shift': <LogicalKeyboardKey?>[null, LogicalKeyboardKey.shiftLeft, LogicalKeyboardKey.shiftRight, null],
+  'Shift': <LogicalKeyboardKey?>[LogicalKeyboardKey.shiftLeft, LogicalKeyboardKey.shiftLeft, LogicalKeyboardKey.shiftRight, null],
 };
 
 /// Maps Windows KeyboardEvent codes to the matching [LogicalKeyboardKey].
diff --git a/packages/flutter/test/services/raw_keyboard_test.dart b/packages/flutter/test/services/raw_keyboard_test.dart
index 45d801c8f90..033e07686e4 100644
--- a/packages/flutter/test/services/raw_keyboard_test.dart
+++ b/packages/flutter/test/services/raw_keyboard_test.dart
@@ -2479,6 +2479,14 @@ void main() {
       RawKeyEventDataWeb.modifierScrollLock: ModifierKey.scrollLockModifier,
     };
 
+    const Map<String, LogicalKeyboardKey> modifierTestsWithNoLocation =
+        <String, LogicalKeyboardKey>{
+      'Alt': LogicalKeyboardKey.altLeft,
+      'Shift': LogicalKeyboardKey.shiftLeft,
+      'Control': LogicalKeyboardKey.controlLeft,
+      'Meta': LogicalKeyboardKey.metaLeft,
+    };
+
     test('modifier keys are recognized individually', () {
       for (final int modifier in modifierTests.keys) {
         final RawKeyEvent event = RawKeyEvent.fromMessage(<String, Object?>{
@@ -2539,6 +2547,19 @@ void main() {
       }
     });
 
+    test('modifier keys with no location are mapped to left', () {
+      for (final String modifierKey in modifierTestsWithNoLocation.keys) {
+        final RawKeyEvent event = RawKeyEvent.fromMessage(<String, Object?>{
+          'type': 'keydown',
+          'keymap': 'web',
+          'key': modifierKey,
+          'location': 0,
+        });
+        final RawKeyEventDataWeb data = event.data as RawKeyEventDataWeb;
+        expect(data.logicalKey, modifierTestsWithNoLocation[modifierKey]);
+      }
+    });
+
     test('Lower letter keys are correctly translated', () {
       final RawKeyEvent keyAEvent = RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
diff --git a/packages/flutter_test/lib/src/event_simulation.dart b/packages/flutter_test/lib/src/event_simulation.dart
index aee135812cd..92ccb7e7f91 100644
--- a/packages/flutter_test/lib/src/event_simulation.dart
+++ b/packages/flutter_test/lib/src/event_simulation.dart
@@ -169,7 +169,7 @@ class KeyEventSimulator {
   static _WebKeyLocationPair _getWebKeyLocation(LogicalKeyboardKey key, String keyLabel) {
     String? result;
     for (final MapEntry<String, List<LogicalKeyboardKey?>> entry in kWebLocationMap.entries) {
-      final int foundIndex = entry.value.indexOf(key);
+      final int foundIndex = entry.value.lastIndexOf(key);
       // If foundIndex is -1, then the key is not defined in kWebLocationMap.
       // If foundIndex is 0, then the key is in the standard part of the keyboard,
       // but we have to check `keyLabel` to see if it's remapped or modified.