diff --git a/src/parseRawGrammar.ts b/src/parseRawGrammar.ts
index f64614d..7373862 100644
--- a/src/parseRawGrammar.ts
+++ b/src/parseRawGrammar.ts
@@ -8,7 +8,7 @@ import { DebugFlags } from './debug';
 import { parseJSON } from './json';
 
 export function parseRawGrammar(content: string, filePath: string | null = null): IRawGrammar {
-	if (filePath !== null && /\.json$/.test(filePath)) {
+	if (filePath !== null && /\.json$/i.test(filePath)) {
 		return parseJSONGrammar(content, filePath);
 	}
 	return parsePLISTGrammar(content, filePath);
diff --git a/src/tests/parseRawGrammar.test.ts b/src/tests/parseRawGrammar.test.ts
new file mode 100644
index 0000000..7d23d04
--- /dev/null
+++ b/src/tests/parseRawGrammar.test.ts
@@ -0,0 +1,14 @@
+/*---------------------------------------------------------
+ * Copyright (C) Microsoft Corporation. All rights reserved.
+ *--------------------------------------------------------*/
+
+import { test } from 'vitest';
+import * as assert from 'assert';
+import { parseRawGrammar } from '../main';
+
+test('JSON grammars load with uppercase file extensions', () => {
+	const source = '{"scopeName":"source.example","patterns":[]}';
+	const expected = parseRawGrammar(source, 'example.json');
+	assert.deepStrictEqual(parseRawGrammar(source, 'example.JSON'), expected);
+	assert.deepStrictEqual(parseRawGrammar(source, 'example.Json'), expected);
+});