diff --git a/__tests__/index.test.jsx b/__tests__/index.test.jsx
index 3e9ae8d..51dd14e 100644
--- a/__tests__/index.test.jsx
+++ b/__tests__/index.test.jsx
@@ -1,7 +1,7 @@
 const { fireEvent, render } = require('@testing-library/react');
 const React = require('react');
 
-const { Variable, VARIABLE_REGEXP } = require('../index');
+const { Variable, VARIABLE_REGEXP, MDX_VARIABLE_REGEXP } = require('../index');
 
 describe('single variable', () => {
   const props = {
@@ -238,3 +238,45 @@ describe('VARIABLE_REGEXP', () => {
     expect('<<what the\r\nfuck>>').not.toMatch(new RegExp(VARIABLE_REGEXP));
   });
 });
+
+describe('MDX_VARIABLE_REGEXP', () => {
+  it('should **not** match against periods', () => {
+    expect('{user.api.key}').not.toMatch(new RegExp(MDX_VARIABLE_REGEXP));
+  });
+
+  it('should **not** match against hyphens', () => {
+    expect('{user.api-key}').not.toMatch(new RegExp(MDX_VARIABLE_REGEXP));
+  });
+
+  it('should **not** match against spaces', () => {
+    expect('{user.api key}').not.toMatch(new RegExp(MDX_VARIABLE_REGEXP));
+  });
+
+  it('should **not match against colons', () => {
+    expect('{user.glossary:term}').not.toMatch(new RegExp(MDX_VARIABLE_REGEXP));
+  });
+
+  it('should match against underscores', () => {
+    expect('{user.api_key}').toMatch(new RegExp(MDX_VARIABLE_REGEXP));
+  });
+
+  it('should be case insensitive', () => {
+    expect('{user.apiKeY}').toMatch(new RegExp(MDX_VARIABLE_REGEXP));
+  });
+
+  it('should match non-leading numeric characters', () => {
+    expect('{user.P2P}').toMatch(new RegExp(MDX_VARIABLE_REGEXP));
+    expect('{user.123}').not.toMatch(new RegExp(MDX_VARIABLE_REGEXP));
+    expect('{user.A123}').toMatch(new RegExp(MDX_VARIABLE_REGEXP));
+  });
+
+  it('should match non-english characters', () => {
+    expect('{user.片仮名}').toMatch(new RegExp(MDX_VARIABLE_REGEXP));
+  });
+
+  it('should NOT match against newlines', () => {
+    expect('{user.what_the\nfuck}').not.toMatch(new RegExp(MDX_VARIABLE_REGEXP));
+    expect('{user.what_the\rfuck}').not.toMatch(new RegExp(MDX_VARIABLE_REGEXP));
+    expect('{user.what_the\r\nfuck}').not.toMatch(new RegExp(MDX_VARIABLE_REGEXP));
+  });
+});
diff --git a/index.jsx b/index.jsx
index ce7ce21..0f25267 100644
--- a/index.jsx
+++ b/index.jsx
@@ -195,5 +195,16 @@ module.exports.Variable = Variable;
 // - <<apiKey>> - regular variables
 // - <<glossary:glossary items>> - glossary
 module.exports.VARIABLE_REGEXP = /(?:\\)?<<((?:(?![\r\n])[-_\p{L}:.\s\d])+)(?:\\)?>>/iu.source;
+
+/**
+ * @example `{user.api_key}`
+ * @example `{user.apiKeY}`
+ * @example `{user.片仮名}`
+ * @example `{user.P2P}`
+ * @see {@link https://stackoverflow.com/a/6926184}
+ */
+module.exports.MDX_VARIABLE_REGEXP =
+  /(\\)?\{user.[$_\p{L}][$_\p{L}\p{Mn}\p{Mc}\p{Nd}\p{Pc}\u200C\u200D]*(\\)?\}/iu.source;
+
 module.exports.VariablesContext = VariablesContext;
 module.exports.SelectedAppContext = SelectedAppContext;