diff --git a/src/main/python/any_keycode_dialog.py b/src/main/python/any_keycode_dialog.py
new file mode 100644
index 0000000..69b155a
--- /dev/null
+++ b/src/main/python/any_keycode_dialog.py
@@ -0,0 +1,55 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+from PyQt5.QtWidgets import QDialog, QDialogButtonBox, QVBoxLayout, QLineEdit, QLabel
+
+from simpleeval import simple_eval
+
+from util import tr
+
+
+class AnyKeycodeDialog(QDialog):
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        self.setWindowTitle(tr("AnyKeycodeDialog", "Enter an arbitrary keycode"))
+
+        self.buttons = QDialogButtonBox(QDialogButtonBox.Ok | QDialogButtonBox.Cancel)
+        self.buttons.accepted.connect(self.accept)
+        self.buttons.rejected.connect(self.reject)
+
+        self.lbl_computed = QLabel()
+        self.txt_entry = QLineEdit()
+        self.txt_entry.textChanged.connect(self.on_change)
+
+        self.layout = QVBoxLayout()
+        self.layout.addWidget(self.txt_entry)
+        self.layout.addWidget(self.lbl_computed)
+        self.layout.addWidget(self.buttons)
+        self.setLayout(self.layout)
+
+        self.value = -1
+        self.on_change()
+
+    def on_change(self):
+        text = self.txt_entry.text()
+        value = err = None
+        try:
+            value = simple_eval(text)
+        except Exception as e:
+            err = str(e)
+
+        if not text:
+            self.value = -1
+            self.lbl_computed.setText(tr("AnyKeycodeDialog", "Enter an expression"))
+        elif err:
+            self.value = -1
+            self.lbl_computed.setText(tr("AnyKeycodeDialog", "Invalid input: {}").format(err))
+        elif isinstance(value, int):
+            self.value = value
+            self.lbl_computed.setText(tr("AnyKeycodeDialog", "Computed value: 0x{:X}").format(value))
+        else:
+            self.value = -1
+            self.lbl_computed.setText(tr("AnyKeycodeDialog", "Invalid input"))
+
+        self.buttons.button(QDialogButtonBox.Ok).setEnabled(self.value != -1)
diff --git a/src/main/python/tabbed_keycodes.py b/src/main/python/tabbed_keycodes.py
index cb42261..2acd500 100644
--- a/src/main/python/tabbed_keycodes.py
+++ b/src/main/python/tabbed_keycodes.py
@@ -4,6 +4,7 @@ from PyQt5.QtCore import Qt, QSize, pyqtSignal
 from PyQt5.QtWidgets import QTabWidget, QWidget, QPushButton, QScrollArea, QApplication
 from PyQt5.QtGui import QPalette
 
+from any_keycode_dialog import AnyKeycodeDialog
 from constants import KEYCODE_BTN_RATIO
 from flowlayout import FlowLayout
 from keycodes import keycode_tooltip, KEYCODES_BASIC, KEYCODES_ISO, KEYCODES_MACRO, KEYCODES_LAYERS, KEYCODES_QUANTUM, \
@@ -48,6 +49,13 @@ class TabbedKeycodes(QTabWidget):
                 self.layout_layers = layout
             elif tab == self.tab_macro:
                 self.layout_macro = layout
+            elif tab == self.tab_basic:
+                # create the "Any" keycode button
+                btn = SquareButton()
+                btn.setText("Any")
+                btn.setRelSize(KEYCODE_BTN_RATIO)
+                btn.clicked.connect(self.on_any_keycode)
+                layout.addWidget(btn)
 
             self.widgets += self.create_buttons(layout, keycodes)
 
@@ -103,3 +111,8 @@ class TabbedKeycodes(QTabWidget):
                 label = widget.keycode.label
                 widget.setStyleSheet("QPushButton {}")
             widget.setText(label.replace("&", "&&"))
+
+    def on_any_keycode(self):
+        dlg = AnyKeycodeDialog()
+        if dlg.exec_() and dlg.value >= 0:
+            self.keycode_changed.emit(dlg.value)