diff --git a/chapi-ast-typescript/src/main/antlr/TypeScriptParser.g4 b/chapi-ast-typescript/src/main/antlr/TypeScriptParser.g4
index f4d38755..234059ed 100644
--- a/chapi-ast-typescript/src/main/antlr/TypeScriptParser.g4
+++ b/chapi-ast-typescript/src/main/antlr/TypeScriptParser.g4
@@ -211,7 +211,7 @@ typeAnnotation
     ;
 
 callSignature
-    : typeParameters? '(' parameterList? ','? ')' typeAnnotation?
+    : typeParameters? '(' parameterList? ','? ')' typeAnnotation? ';'?
     ;
 
 parameterList
@@ -390,7 +390,7 @@ statementList
     ;
 
 abstractDeclaration
-    : Abstract (Identifier callSignature | variableStatement) eos
+    : Abstract (Identifier '?'? callSignature | variableStatement) eos
     ;
 
 importStatement
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 6081baa4..dd64de67 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
@@ -108,6 +108,15 @@ export class DemoComponent implements OnInit, ControlValueAccessor {
         TypeScriptAnalyser().analysis(code2, "index.tsx")
     }
 
+    @Test
+    fun type_in_interface() {
+        val code = """export abstract class ReactiveOptionProviderService<T extends SelectOption> {
+  abstract create?(name: string): Observable<T>;
+}"""
+
+        TypeScriptAnalyser().analysis(code, "index.tsx")
+    }
+
     @Test
     fun numeric_separators() {
         val code = """if (+value > 1_000_000_000) {