diff --git a/chapi-ast-typescript/src/main/antlr/TypeScriptParser.g4 b/chapi-ast-typescript/src/main/antlr/TypeScriptParser.g4
index 21b46ab9..7d04c226 100644
--- a/chapi-ast-typescript/src/main/antlr/TypeScriptParser.g4
+++ b/chapi-ast-typescript/src/main/antlr/TypeScriptParser.g4
@@ -170,7 +170,7 @@ typeMember
     | indexSignature
     | methodSignature ('=>' type_)?
     | enumSignature
-    | '[' typeReference In (Keyof | Typeof)* typeReference ']' typeAnnotation
+    | '[' typeReference In (Keyof | Typeof)* typeReference ']' '?'? typeAnnotation
     ;
 
 arrayType
diff --git a/chapi-ast-typescript/src/test/kotlin/chapi/ast/typescriptast/TypeScriptRegressionTest.kt b/chapi-ast-typescript/src/test/kotlin/chapi/ast/typescriptast/TypeScriptRegressionTest.kt
index c4cfe86c..c17a3cd0 100644
--- a/chapi-ast-typescript/src/test/kotlin/chapi/ast/typescriptast/TypeScriptRegressionTest.kt
+++ b/chapi-ast-typescript/src/test/kotlin/chapi/ast/typescriptast/TypeScriptRegressionTest.kt
@@ -102,5 +102,8 @@ export class DemoComponent implements OnInit, ControlValueAccessor {
     fun type_definition() {
         val code = """export type Exact<T extends { [key: string]: unknown }> = { [K in keyof T]: T[K] };"""
         TypeScriptAnalyser().analysis(code, "index.tsx")
+
+        val code2 = """export type MakeOptional<T, K extends keyof T> = Omit<T, K> & { [SubKey in K]?: Maybe<T[SubKey]> };"""
+        TypeScriptAnalyser().analysis(code2, "index.tsx")
     }
 }