diff --git a/dev/tools/gen_keycodes/data/key_data.json b/dev/tools/gen_keycodes/data/key_data.json
index accd0d8db6..d17e005354 100644
--- a/dev/tools/gen_keycodes/data/key_data.json
+++ b/dev/tools/gen_keycodes/data/key_data.json
@@ -66,33 +66,6 @@
       "glfw": null
     }
   },
-  "fn": {
-    "names": {
-      "domkey": "Fn",
-      "android": [
-        "FUNCTION"
-      ],
-      "english": "Fn",
-      "chromium": "fn",
-      "glfw": null
-    },
-    "scanCodes": {
-      "android": [
-        464
-      ],
-      "usb": 18,
-      "linux": null,
-      "xkb": null,
-      "windows": null,
-      "macos": null
-    },
-    "keyCodes": {
-      "android": [
-        119
-      ],
-      "glfw": null
-    }
-  },
   "fnLock": {
     "names": {
       "domkey": "FnLock",
@@ -7222,5 +7195,32 @@
       ],
       "glfw": null
     }
+  },
+  "fn": {
+    "names": {
+      "domkey": "Fn",
+      "android": [
+        "FUNCTION"
+      ],
+      "english": "Fn",
+      "chromium": "fn",
+      "glfw": null
+    },
+    "scanCodes": {
+      "android": [
+        464
+      ],
+      "usb": 18,
+      "linux": null,
+      "xkb": null,
+      "windows": null,
+      "macos": 63
+    },
+    "keyCodes": {
+      "android": [
+        119
+      ],
+      "glfw": null
+    }
   }
 }
\ No newline at end of file
diff --git a/dev/tools/gen_keycodes/data/keyboard_key.tmpl b/dev/tools/gen_keycodes/data/keyboard_key.tmpl
index 562d408c4b..8d5ae35d91 100644
--- a/dev/tools/gen_keycodes/data/keyboard_key.tmpl
+++ b/dev/tools/gen_keycodes/data/keyboard_key.tmpl
@@ -238,6 +238,21 @@ class LogicalKeyboardKey extends KeyboardKey {
     return result == null ? <LogicalKeyboardKey>{} : <LogicalKeyboardKey>{result};
   }
 
+  /// Takes a set of keys, and returns the same set, but with any keys that have
+  /// synonyms replaced.
+  ///
+  /// It is used, for example, to make sets of keys with members like
+  /// [controlRight] and [controlLeft] and convert that set to contain just
+  /// [control], so that the question "is any control key down?" can be asked.
+  static Set<LogicalKeyboardKey> collapseSynonyms(Set<LogicalKeyboardKey> input) {
+    final Set<LogicalKeyboardKey> result = <LogicalKeyboardKey>{};
+    for (LogicalKeyboardKey key in input) {
+      final LogicalKeyboardKey synonym = _synonyms[key];
+      result.add(synonym ?? key);
+    }
+    return result;
+  }
+
   @override
   void debugFillProperties(DiagnosticPropertiesBuilder properties) {
     super.debugFillProperties(properties);
diff --git a/dev/tools/gen_keycodes/data/keyboard_maps.tmpl b/dev/tools/gen_keycodes/data/keyboard_maps.tmpl
index 45d90a897e..a6c3dfc61a 100644
--- a/dev/tools/gen_keycodes/data/keyboard_maps.tmpl
+++ b/dev/tools/gen_keycodes/data/keyboard_maps.tmpl
@@ -53,6 +53,12 @@ const Map<int, LogicalKeyboardKey> kMacOsNumPadMap = <int, LogicalKeyboardKey>{
 @@@MACOS_NUMPAD_MAP@@@
 };
 
+/// A map of macOS key codes which are numbered function keys, so that they
+/// can be excluded when asking "is the Fn modifier down?".
+const Map<int, LogicalKeyboardKey> kMacOsFunctionKeyMap = <int, LogicalKeyboardKey>{
+@@@MACOS_FUNCTION_KEY_MAP@@@
+};
+
 /// Maps GLFW-specific key codes to the matching [LogicalKeyboardKey].
 const Map<int, LogicalKeyboardKey> kGlfwToLogicalKey = <int, LogicalKeyboardKey>{
 @@@GLFW_KEY_CODE_MAP@@@
diff --git a/dev/tools/gen_keycodes/data/supplemental_hid_codes.inc b/dev/tools/gen_keycodes/data/supplemental_hid_codes.inc
index da271bc806..b9c99dc814 100644
--- a/dev/tools/gen_keycodes/data/supplemental_hid_codes.inc
+++ b/dev/tools/gen_keycodes/data/supplemental_hid_codes.inc
@@ -43,3 +43,10 @@
   USB_KEYMAP(0x05ff1d, 0x0000, 0x0000, 0x0000, 0xffff, "GameButtonX", BUTTON_X),
   USB_KEYMAP(0x05ff1e, 0x0000, 0x0000, 0x0000, 0xffff, "GameButtonY", BUTTON_Y),
   USB_KEYMAP(0x05ff1f, 0x0000, 0x0000, 0x0000, 0xffff, "GameButtonZ", BUTTON_Z),
+
+  // The Mac defines a key code for the Fn key on Mac keyboards, but it's not
+  // defined on other platforms. Chromium does define an "Fn" row, but doesn't
+  // give it a Mac keycode. This overrides their definition.
+  //        USB HID    evdev    XKB     Win    Mac  DOMKey         Code
+   USB_KEYMAP(0x000012, 0x0000, 0x0000, 0x0000, 0x003f, "Fn", FN),
+
diff --git a/dev/tools/gen_keycodes/lib/code_gen.dart b/dev/tools/gen_keycodes/lib/code_gen.dart
index 1afe2f7809..98897cf4c4 100644
--- a/dev/tools/gen_keycodes/lib/code_gen.dart
+++ b/dev/tools/gen_keycodes/lib/code_gen.dart
@@ -114,6 +114,13 @@ $otherComments  static const LogicalKeyboardKey $constantName = LogicalKeyboardK
     }).toList();
   }
 
+  List<Key> get functionKeyData {
+    final RegExp functionKeyRe = RegExp(r'^f[0-9]+$');
+    return keyData.data.where((Key entry) {
+      return functionKeyRe.hasMatch(entry.constantName);
+    }).toList();
+  }
+
   /// This generates the map of USB HID codes to physical keys.
   String get predefinedHidCodeMap {
     final StringBuffer scanCodeMap = StringBuffer();
@@ -240,6 +247,16 @@ $otherComments  static const LogicalKeyboardKey $constantName = LogicalKeyboardK
     return macOsNumPadMap.toString().trimRight();
   }
 
+  String get macOsFunctionKeyMap {
+    final StringBuffer macOsFunctionKeyMap = StringBuffer();
+    for (Key entry in functionKeyData) {
+      if (entry.macOsScanCode != null) {
+        macOsFunctionKeyMap.writeln('  ${toHex(entry.macOsScanCode)}: LogicalKeyboardKey.${entry.constantName},');
+      }
+    }
+    return macOsFunctionKeyMap.toString().trimRight();
+  }
+
   /// This generates the map of Fuchsia key codes to logical keys.
   String get fuchsiaKeyCodeMap {
     final StringBuffer fuchsiaKeyCodeMap = StringBuffer();
@@ -324,6 +341,7 @@ $otherComments  static const LogicalKeyboardKey $constantName = LogicalKeyboardK
       'FUCHSIA_KEY_CODE_MAP': fuchsiaKeyCodeMap,
       'MACOS_SCAN_CODE_MAP': macOsScanCodeMap,
       'MACOS_NUMPAD_MAP': macOsNumpadMap,
+      'MACOS_FUNCTION_KEY_MAP': macOsFunctionKeyMap,
       'GLFW_KEY_CODE_MAP': glfwKeyCodeMap,
       'GLFW_NUMPAD_MAP': glfwNumpadMap,
       'XKB_SCAN_CODE_MAP': xkbScanCodeMap,
diff --git a/dev/tools/gen_keycodes/lib/key_data.dart b/dev/tools/gen_keycodes/lib/key_data.dart
index ced5fb0e4f..56b4d88566 100644
--- a/dev/tools/gen_keycodes/lib/key_data.dart
+++ b/dev/tools/gen_keycodes/lib/key_data.dart
@@ -244,6 +244,9 @@ class KeyData {
           // Skip key that is not actually generated by any keyboard.
           return '';
         }
+        // Remove duplicates: last one wins, so that supplemental codes
+        // override.
+        entries.removeWhere((Key entry) => entry.usbHidCode == newEntry.usbHidCode);
         entries.add(newEntry);
       }
       return match.group(0);
diff --git a/packages/flutter/lib/src/services/keyboard_key.dart b/packages/flutter/lib/src/services/keyboard_key.dart
index 3bf138b0a6..41446b563b 100644
--- a/packages/flutter/lib/src/services/keyboard_key.dart
+++ b/packages/flutter/lib/src/services/keyboard_key.dart
@@ -315,11 +315,6 @@ class LogicalKeyboardKey extends KeyboardKey {
   /// See the function [RawKeyEvent.logicalKey] for more information.
   static const LogicalKeyboardKey superKey = LogicalKeyboardKey(0x00100000011, debugName: kReleaseMode ? null : 'Super Key');
 
-  /// Represents the logical "Fn" key on the keyboard.
-  ///
-  /// See the function [RawKeyEvent.logicalKey] for more information.
-  static const LogicalKeyboardKey fn = LogicalKeyboardKey(0x00100000012, debugName: kReleaseMode ? null : 'Fn');
-
   /// Represents the logical "Fn Lock" key on the keyboard.
   ///
   /// See the function [RawKeyEvent.logicalKey] for more information.
@@ -1625,6 +1620,11 @@ class LogicalKeyboardKey extends KeyboardKey {
   /// See the function [RawKeyEvent.logicalKey] for more information.
   static const LogicalKeyboardKey gameButtonZ = LogicalKeyboardKey(0x0010005ff1f, debugName: kReleaseMode ? null : 'Game Button Z');
 
+  /// Represents the logical "Fn" key on the keyboard.
+  ///
+  /// See the function [RawKeyEvent.logicalKey] for more information.
+  static const LogicalKeyboardKey fn = LogicalKeyboardKey(0x00100000012, debugName: kReleaseMode ? null : 'Fn');
+
   /// Represents the logical "Shift" key on the keyboard.
   ///
   /// This key represents the union of the keys {shiftLeft, shiftRight} when
@@ -1659,7 +1659,6 @@ class LogicalKeyboardKey extends KeyboardKey {
     0x0100000000: none,
     0x0100000010: hyper,
     0x0100000011: superKey,
-    0x0100000012: fn,
     0x0100000013: fnLock,
     0x0100000014: suspend,
     0x0100000015: resume,
@@ -1921,6 +1920,7 @@ class LogicalKeyboardKey extends KeyboardKey {
     0x010005ff1d: gameButtonX,
     0x010005ff1e: gameButtonY,
     0x010005ff1f: gameButtonZ,
+    0x0100000012: fn,
     0x201000700e1: shift,
     0x201000700e3: meta,
     0x201000700e2: alt,
@@ -2102,11 +2102,6 @@ class PhysicalKeyboardKey extends KeyboardKey {
   /// See the function [RawKeyEvent.physicalKey] for more information.
   static const PhysicalKeyboardKey superKey = PhysicalKeyboardKey(0x00000011, debugName: kReleaseMode ? null : 'Super Key');
 
-  /// Represents the location of the "Fn" key on a generalized keyboard.
-  ///
-  /// See the function [RawKeyEvent.physicalKey] for more information.
-  static const PhysicalKeyboardKey fn = PhysicalKeyboardKey(0x00000012, debugName: kReleaseMode ? null : 'Fn');
-
   /// Represents the location of the "Fn Lock" key on a generalized keyboard.
   ///
   /// See the function [RawKeyEvent.physicalKey] for more information.
@@ -3526,13 +3521,17 @@ class PhysicalKeyboardKey extends KeyboardKey {
   /// See the function [RawKeyEvent.physicalKey] for more information.
   static const PhysicalKeyboardKey gameButtonZ = PhysicalKeyboardKey(0x0005ff1f, debugName: kReleaseMode ? null : 'Game Button Z');
 
+  /// Represents the location of the "Fn" key on a generalized keyboard.
+  ///
+  /// See the function [RawKeyEvent.physicalKey] for more information.
+  static const PhysicalKeyboardKey fn = PhysicalKeyboardKey(0x00000012, debugName: kReleaseMode ? null : 'Fn');
+
   // A list of all the predefined constant PhysicalKeyboardKeys so that they
   // can be searched.
   static const Map<int, PhysicalKeyboardKey> _knownPhysicalKeys = <int, PhysicalKeyboardKey>{
     0x00000000: none,
     0x00000010: hyper,
     0x00000011: superKey,
-    0x00000012: fn,
     0x00000013: fnLock,
     0x00000014: suspend,
     0x00000015: resume,
@@ -3794,5 +3793,6 @@ class PhysicalKeyboardKey extends KeyboardKey {
     0x0005ff1d: gameButtonX,
     0x0005ff1e: gameButtonY,
     0x0005ff1f: gameButtonZ,
+    0x00000012: fn,
   };
 }
diff --git a/packages/flutter/lib/src/services/keyboard_maps.dart b/packages/flutter/lib/src/services/keyboard_maps.dart
index f5030d959d..099039e2c2 100644
--- a/packages/flutter/lib/src/services/keyboard_maps.dart
+++ b/packages/flutter/lib/src/services/keyboard_maps.dart
@@ -14,7 +14,6 @@ import 'keyboard_key.dart';
 /// Maps Android-specific key codes to the matching [LogicalKeyboardKey].
 const Map<int, LogicalKeyboardKey> kAndroidToLogicalKey = <int, LogicalKeyboardKey>{
   0: LogicalKeyboardKey.none,
-  119: LogicalKeyboardKey.fn,
   223: LogicalKeyboardKey.sleep,
   224: LogicalKeyboardKey.wakeUp,
   29: LogicalKeyboardKey.keyA,
@@ -194,11 +193,11 @@ const Map<int, LogicalKeyboardKey> kAndroidToLogicalKey = <int, LogicalKeyboardK
   99: LogicalKeyboardKey.gameButtonX,
   100: LogicalKeyboardKey.gameButtonY,
   101: LogicalKeyboardKey.gameButtonZ,
+  119: LogicalKeyboardKey.fn,
 };
 
 /// Maps Android-specific scan codes to the matching [PhysicalKeyboardKey].
 const Map<int, PhysicalKeyboardKey> kAndroidToPhysicalKey = <int, PhysicalKeyboardKey>{
-  464: PhysicalKeyboardKey.fn,
   205: PhysicalKeyboardKey.suspend,
   142: PhysicalKeyboardKey.sleep,
   143: PhysicalKeyboardKey.wakeUp,
@@ -425,6 +424,7 @@ const Map<int, PhysicalKeyboardKey> kAndroidToPhysicalKey = <int, PhysicalKeyboa
   307: PhysicalKeyboardKey.gameButtonX,
   308: PhysicalKeyboardKey.gameButtonY,
   309: PhysicalKeyboardKey.gameButtonZ,
+  464: PhysicalKeyboardKey.fn,
 };
 
 /// A map of Android key codes which have printable representations, but appear
@@ -457,7 +457,6 @@ const Map<int, LogicalKeyboardKey> kFuchsiaToLogicalKey = <int, LogicalKeyboardK
   0x100000000: LogicalKeyboardKey.none,
   0x100000010: LogicalKeyboardKey.hyper,
   0x100000011: LogicalKeyboardKey.superKey,
-  0x100000012: LogicalKeyboardKey.fn,
   0x100000013: LogicalKeyboardKey.fnLock,
   0x100000014: LogicalKeyboardKey.suspend,
   0x100000015: LogicalKeyboardKey.resume,
@@ -719,6 +718,7 @@ const Map<int, LogicalKeyboardKey> kFuchsiaToLogicalKey = <int, LogicalKeyboardK
   0x10005ff1d: LogicalKeyboardKey.gameButtonX,
   0x10005ff1e: LogicalKeyboardKey.gameButtonY,
   0x10005ff1f: LogicalKeyboardKey.gameButtonZ,
+  0x100000012: LogicalKeyboardKey.fn,
 };
 
 /// Maps Fuchsia-specific USB HID Usage IDs to the matching
@@ -727,7 +727,6 @@ const Map<int, PhysicalKeyboardKey> kFuchsiaToPhysicalKey = <int, PhysicalKeyboa
   0x00000000: PhysicalKeyboardKey.none,
   0x00000010: PhysicalKeyboardKey.hyper,
   0x00000011: PhysicalKeyboardKey.superKey,
-  0x00000012: PhysicalKeyboardKey.fn,
   0x00000013: PhysicalKeyboardKey.fnLock,
   0x00000014: PhysicalKeyboardKey.suspend,
   0x00000015: PhysicalKeyboardKey.resume,
@@ -989,6 +988,7 @@ const Map<int, PhysicalKeyboardKey> kFuchsiaToPhysicalKey = <int, PhysicalKeyboa
   0x0005ff1d: PhysicalKeyboardKey.gameButtonX,
   0x0005ff1e: PhysicalKeyboardKey.gameButtonY,
   0x0005ff1f: PhysicalKeyboardKey.gameButtonZ,
+  0x00000012: PhysicalKeyboardKey.fn,
 };
 
 /// Maps macOS-specific key code values representing [PhysicalKeyboardKey].
@@ -1113,6 +1113,7 @@ const Map<int, PhysicalKeyboardKey> kMacOsToPhysicalKey = <int, PhysicalKeyboard
   0x0000003c: PhysicalKeyboardKey.shiftRight,
   0x0000003d: PhysicalKeyboardKey.altRight,
   0x00000036: PhysicalKeyboardKey.metaRight,
+  0x0000003f: PhysicalKeyboardKey.fn,
 };
 
 /// A map of macOS key codes which have printable representations, but appear
@@ -1138,6 +1139,31 @@ const Map<int, LogicalKeyboardKey> kMacOsNumPadMap = <int, LogicalKeyboardKey>{
   0x0000005f: LogicalKeyboardKey.numpadComma,
 };
 
+/// A map of macOS key codes which are numbered function keys, so that they
+/// can be excluded when asking "is the Fn modifier down?".
+const Map<int, LogicalKeyboardKey> kMacOsFunctionKeyMap = <int, LogicalKeyboardKey>{
+  0x0000007a: LogicalKeyboardKey.f1,
+  0x00000078: LogicalKeyboardKey.f2,
+  0x00000063: LogicalKeyboardKey.f3,
+  0x00000076: LogicalKeyboardKey.f4,
+  0x00000060: LogicalKeyboardKey.f5,
+  0x00000061: LogicalKeyboardKey.f6,
+  0x00000062: LogicalKeyboardKey.f7,
+  0x00000064: LogicalKeyboardKey.f8,
+  0x00000065: LogicalKeyboardKey.f9,
+  0x0000006d: LogicalKeyboardKey.f10,
+  0x00000067: LogicalKeyboardKey.f11,
+  0x0000006f: LogicalKeyboardKey.f12,
+  0x00000069: LogicalKeyboardKey.f13,
+  0x0000006b: LogicalKeyboardKey.f14,
+  0x00000071: LogicalKeyboardKey.f15,
+  0x0000006a: LogicalKeyboardKey.f16,
+  0x00000040: LogicalKeyboardKey.f17,
+  0x0000004f: LogicalKeyboardKey.f18,
+  0x00000050: LogicalKeyboardKey.f19,
+  0x0000005a: LogicalKeyboardKey.f20,
+};
+
 /// Maps GLFW-specific key codes to the matching [LogicalKeyboardKey].
 const Map<int, LogicalKeyboardKey> kGlfwToLogicalKey = <int, LogicalKeyboardKey>{
   65: LogicalKeyboardKey.keyA,
@@ -1498,7 +1524,6 @@ const Map<String, LogicalKeyboardKey> kWebToLogicalKey = <String, LogicalKeyboar
   'None': LogicalKeyboardKey.none,
   'Hyper': LogicalKeyboardKey.hyper,
   'Super': LogicalKeyboardKey.superKey,
-  'Fn': LogicalKeyboardKey.fn,
   'FnLock': LogicalKeyboardKey.fnLock,
   'Suspend': LogicalKeyboardKey.suspend,
   'Resume': LogicalKeyboardKey.resume,
@@ -1723,6 +1748,7 @@ const Map<String, LogicalKeyboardKey> kWebToLogicalKey = <String, LogicalKeyboar
   'GameButtonX': LogicalKeyboardKey.gameButtonX,
   'GameButtonY': LogicalKeyboardKey.gameButtonY,
   'GameButtonZ': LogicalKeyboardKey.gameButtonZ,
+  'Fn': LogicalKeyboardKey.fn,
 };
 
 /// Maps Web KeyboardEvent codes to the matching [PhysicalKeyboardKey].
@@ -1730,7 +1756,6 @@ const Map<String, PhysicalKeyboardKey> kWebToPhysicalKey = <String, PhysicalKeyb
   'None': PhysicalKeyboardKey.none,
   'Hyper': PhysicalKeyboardKey.hyper,
   'Super': PhysicalKeyboardKey.superKey,
-  'Fn': PhysicalKeyboardKey.fn,
   'FnLock': PhysicalKeyboardKey.fnLock,
   'Suspend': PhysicalKeyboardKey.suspend,
   'Resume': PhysicalKeyboardKey.resume,
@@ -1955,6 +1980,7 @@ const Map<String, PhysicalKeyboardKey> kWebToPhysicalKey = <String, PhysicalKeyb
   'GameButtonX': PhysicalKeyboardKey.gameButtonX,
   'GameButtonY': PhysicalKeyboardKey.gameButtonY,
   'GameButtonZ': PhysicalKeyboardKey.gameButtonZ,
+  'Fn': PhysicalKeyboardKey.fn,
 };
 
 /// A map of Web KeyboardEvent codes which have printable representations, but appear
diff --git a/packages/flutter/lib/src/services/raw_keyboard.dart b/packages/flutter/lib/src/services/raw_keyboard.dart
index 2b785ea41d..cf345ab18a 100644
--- a/packages/flutter/lib/src/services/raw_keyboard.dart
+++ b/packages/flutter/lib/src/services/raw_keyboard.dart
@@ -502,6 +502,15 @@ class RawKeyboard {
     if (event == null) {
       return;
     }
+    if (event.data is RawKeyEventDataMacOs && event.logicalKey == LogicalKeyboardKey.fn) {
+      // On macOS laptop keyboards, the fn key is used to generate home/end and
+      // f1-f12, but it ALSO generates a separate down/up event for the fn key
+      // itself. Other platforms hide the fn key, and just produce the key that
+      // it is combined with, so to keep it possible to write cross platform
+      // code that looks at which keys are pressed, the fn key is ignored on
+      // macOS.
+      return;
+    }
     if (event is RawKeyDownEvent) {
       _keysPressed.add(event.logicalKey);
     }
@@ -561,7 +570,6 @@ class RawKeyboard {
     LogicalKeyboardKey.capsLock,
     LogicalKeyboardKey.numLock,
     LogicalKeyboardKey.scrollLock,
-    LogicalKeyboardKey.fn,
   };
 
   void _synchronizeModifiers(RawKeyEvent event) {
@@ -580,6 +588,10 @@ class RawKeyboard {
     // pressed/released while the app doesn't have focus, to make sure that
     // _keysPressed reflects reality at all times.
     _keysPressed.removeAll(_allModifiers);
+    if (event.data is! RawKeyEventDataFuchsia && event.data is! RawKeyEventDataMacOs) {
+      // On Fuchsia and macOS, the Fn key is not considered a modifier key.
+      _keysPressed.remove(LogicalKeyboardKey.fn);
+    }
     _keysPressed.addAll(modifierKeys);
   }
 
diff --git a/packages/flutter/test/services/raw_keyboard_test.dart b/packages/flutter/test/services/raw_keyboard_test.dart
index 98743342a9..692cb8d8b5 100644
--- a/packages/flutter/test/services/raw_keyboard_test.dart
+++ b/packages/flutter/test/services/raw_keyboard_test.dart
@@ -22,7 +22,7 @@ void main() {
         expect(
           RawKeyboard.instance.keysPressed,
           equals(
-            <LogicalKeyboardKey>{LogicalKeyboardKey.shiftLeft},
+            <LogicalKeyboardKey>{ LogicalKeyboardKey.shiftLeft },
           ),
           reason: 'on $platform',
         );
@@ -64,12 +64,44 @@ void main() {
         expect(
           RawKeyboard.instance.keysPressed,
           equals(
-            <LogicalKeyboardKey>{LogicalKeyboardKey.shiftLeft},
+            <LogicalKeyboardKey>{ LogicalKeyboardKey.shiftLeft },
           ),
           reason: 'on $platform',
         );
         await simulateKeyUpEvent(LogicalKeyboardKey.shiftLeft, platform: platform);
         expect(RawKeyboard.instance.keysPressed, isEmpty, reason: 'on $platform');
+        // The Fn key isn't mapped on linux.
+        if (platform != 'linux') {
+          await simulateKeyDownEvent(LogicalKeyboardKey.fn, platform: platform);
+          expect(RawKeyboard.instance.keysPressed,
+            equals(
+              <LogicalKeyboardKey>{
+                if (platform != 'macos') LogicalKeyboardKey.fn,
+              },
+            ),
+            reason: 'on $platform');
+          await simulateKeyDownEvent(LogicalKeyboardKey.f12, platform: platform);
+          expect(
+            RawKeyboard.instance.keysPressed,
+            equals(
+              <LogicalKeyboardKey>{
+                if (platform != 'macos') LogicalKeyboardKey.fn,
+                LogicalKeyboardKey.f12,
+              },
+            ),
+            reason: 'on $platform',
+          );
+          await simulateKeyUpEvent(LogicalKeyboardKey.fn, platform: platform);
+          expect(
+            RawKeyboard.instance.keysPressed,
+            equals(
+              <LogicalKeyboardKey>{ LogicalKeyboardKey.f12 },
+            ),
+            reason: 'on $platform',
+          );
+          await simulateKeyUpEvent(LogicalKeyboardKey.f12, platform: platform);
+          expect(RawKeyboard.instance.keysPressed, isEmpty, reason: 'on $platform');
+        }
       }
     }, skip: kIsWeb);