diff --git a/CHANGELOG.md b/CHANGELOG.md
index 915ec5f..613bc40 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@
 - Added support for error declaration grammar.
 - Added support for declaration function call grammar.
 - Added support for comment grammar.
+- Added support for index declaration grammar.
 
 ## [0.0.2] - 2023-01-01
 
diff --git a/syntaxes/polylang.tmLanguage.json b/syntaxes/polylang.tmLanguage.json
index e2d25ef..c75fbe7 100644
--- a/syntaxes/polylang.tmLanguage.json
+++ b/syntaxes/polylang.tmLanguage.json
@@ -48,7 +48,8 @@
 				{"include": "#declaration-storage"},
 				{"include": "#declaration-function"},
 				{"include": "#declaration-error"},
-				{"include": "#declaration-call"}
+				{"include": "#declaration-call"},
+				{"include": "#declaration-index"}
 			]
 		},
 		"declaration-collection": {
@@ -79,6 +80,10 @@
 			"match": "\\b([A-Za-z_]\\w*)\\s*(\\()",
 			"name": "entity.name.function.call.polylang"
 		},
+		"declaration-index": {
+			"match": "(@index|@unique)\\b",
+			"name": "keyword.control.index.polylang"
+		},
 		"operator": {
 			"patterns": [
 				{"include": "#operator-binary"},