diff --git a/backend/src/middlewares/request-validators/room-validator.middleware.ts b/backend/src/middlewares/request-validators/room-validator.middleware.ts
index 60f7eb7..b32b478 100644
--- a/backend/src/middlewares/request-validators/room-validator.middleware.ts
+++ b/backend/src/middlewares/request-validators/room-validator.middleware.ts
@@ -99,7 +99,7 @@ const RoomThemeSchema = z.object({
 		.string()
 		.min(1, 'Theme name cannot be empty')
 		.max(50, 'Theme name cannot exceed 50 characters')
-		.regex(/^[a-z0-9_-]+$/, 'Theme name can only contain lowercase letters, numbers, hyphens and underscores'),
+		.regex(/^[a-zA-Z0-9_-]+$/, 'Theme name can only contain letters, numbers, hyphens and underscores'),
 	enabled: z.boolean(),
 	baseTheme: ThemeModeSchema,
 	backgroundColor: hexColorSchema.optional(),
diff --git a/backend/tests/integration/api/global-config/appearance.test.ts b/backend/tests/integration/api/global-config/appearance.test.ts
index 0f709c0..f0149db 100644
--- a/backend/tests/integration/api/global-config/appearance.test.ts
+++ b/backend/tests/integration/api/global-config/appearance.test.ts
@@ -182,12 +182,9 @@ describe('Rooms Appearance Config API Tests', () => {
 
 		it('should reject when theme name has invalid characters', async () => {
 			const invalidNames = [
-				'Corporate Blue', // Uppercase and spaces
-				'dark-mode-2024!', // Exclamation mark
-				'theme.corporate', // Dot
-				'Dark_Mode', // Uppercase
-				'theme 1', // Space
-				'thème-français' // Accents
+				'Corporate Blue', // Spaces
+				'dark-mode.2024!', // Special characters
+				'thème_français' // Accents
 			];
 
 			for (const name of invalidNames) {
@@ -206,7 +203,7 @@ describe('Rooms Appearance Config API Tests', () => {
 				expectValidationError(
 					response,
 					'appearance.themes.0.name',
-					'Theme name can only contain lowercase letters, numbers, hyphens and underscores'
+					'Theme name can only contain letters, numbers, hyphens and underscores'
 				);
 			}
 		});