diff --git a/README.md b/README.md
index 363bfaf..56fe937 100644
--- a/README.md
+++ b/README.md
@@ -8,13 +8,17 @@ Use <kbd>Alt</kbd> + <kbd>click</kbd> to jump to a definition using your mouse,
 
 ![Go to definition](https://raw.githubusercontent.com/krassowski/jupyterlab-go-to-definition/master/examples/demo.gif)
 
-You can replace the key modifier for mouse click from <kbd>Alt</kbd> to <kbd>Control</kbd>, <kbd>Shift</kbd>, <kbd>Meta</kbd> or <kbd>AltGraph</kbd> in the settings.
+You can replace the key modifier for mouse click from <kbd>Alt</kbd> to <kbd>Control</kbd>, <kbd>Shift</kbd>, <kbd>Meta</kbd> or <kbd>AltGraph</kbd> in the settings*.
 
 To jump back to the variable/function usage, use <kbd>Alt</kbd> + <kbd>o</kbd>.
 
 The plugin is language-agnostic, though optimized for Python. Initial support for R was recently implemented.
 Support for other languages is possible (PRs welcome).
 
+*) For full list of physical keys mapped to the modifiers (which depend on your Operating System), please see [the MDN documentation](https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/getModifierState).
+
+Safari users: Safari does not implement `MouseEvent.getModifierState` (see [#3](https://github.com/krassowski/jupyterlab-go-to-definition/issues/3)), thus only <kbd>Alt</kbd>, <kbd>Control</kbd>, <kbd>Shift</kbd> and <kbd>Meta</kbd> are supported.
+
 ## Prerequisites
 
 * JupyterLab
diff --git a/package.json b/package.json
index db6a188..ca16d86 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@krassowski/jupyterlab_go_to_definition",
-  "version": "0.1.4",
+  "version": "0.1.5",
   "description": "Jump to definition of a variable or function in JupyterLab",
   "keywords": [
     "jupyter",
diff --git a/src/editors/codemirror/extension.ts b/src/editors/codemirror/extension.ts
index aafd337..3433c1c 100644
--- a/src/editors/codemirror/extension.ts
+++ b/src/editors/codemirror/extension.ts
@@ -9,6 +9,31 @@ import { CodeMirrorTokensProvider } from "./tokens";
 const HANDLERS_ON = '_go_to_are_handlers_on';
 
 
+function getModifierState(event: MouseEvent, modifierKey: string): boolean {
+  // Note: Safari does not support getModifierState on MouseEvent, see:
+  // https://github.com/krassowski/jupyterlab-go-to-definition/issues/3
+  // thus AltGraph and others are not supported on Safari
+  // Full list of modifier keys and mappings to physical keys on different OSes:
+  // https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/getModifierState
+
+  if (event.getModifierState !== undefined) {
+    return event.getModifierState(modifierKey)
+  }
+
+  switch (modifierKey) {
+    case 'Shift':
+      return event.shiftKey;
+    case 'Alt':
+      return event.altKey;
+    case 'Control':
+      return event.ctrlKey;
+    case 'Meta':
+      return event.metaKey;
+  }
+}
+
+
+
 export class CodeMirrorExtension extends CodeMirrorTokensProvider implements IEditorExtension {
 
   jumper: CodeJumper;
@@ -44,7 +69,7 @@ export class CodeMirrorExtension extends CodeMirrorTokensProvider implements IEd
         //codemirror_editor.addKeydownHandler()
         let target = event.target as HTMLElement;
         const {button} = event;
-        if (button === 0 && event.getModifierState(CodeMirrorExtension.modifierKey as string)) {
+        if (button === 0 && getModifierState(event, CodeMirrorExtension.modifierKey as string)) {
 
           const classes = ['cm-variable', 'cm-property'];