diff --git a/ets2panda/parser/ETSparserTypes.cpp b/ets2panda/parser/ETSparserTypes.cpp
index 946e7611eda6860a9524045f088f7a7dd09d57ef..70533af98d965f246f68781b78f64747d297bb36 100644
--- a/ets2panda/parser/ETSparserTypes.cpp
+++ b/ets2panda/parser/ETSparserTypes.cpp
@@ -556,15 +556,31 @@ ir::TypeNode *ETSParser::ParseTypeAnnotation(TypeAnnotationParsingOptions *optio
         LogError(diagnostic::INVALID_TYPE);
         return AllocBrokenType(beforeTypeAnnotation);
     }
-    if (!typeAnnotation->IsTSArrayType() && !typeAnnotation->IsETSTuple() &&
-        !(typeAnnotation->IsETSTypeReference() &&
-          typeAnnotation->AsETSTypeReference()->BaseName()->Name() == compiler::Signatures::ARRAY)) {
+    if (typeAnnotation->IsETSUnionType()) {
+        auto *unionType = typeAnnotation->AsETSUnionType();
+        bool hasApplicableType = false;
+        for (auto *subType : unionType->Types()) {
+            if (subType->IsTSArrayType() || subType->IsETSTuple() ||
+                (subType->IsETSTypeReference() &&
+                 subType->AsETSTypeReference()->BaseName()->Name() == compiler::Signatures::ARRAY)) {
+                hasApplicableType = true;
+                break;
+            }
+        }
+
+        if (!hasApplicableType) {
+            LogError(diagnostic::READONLY_ONLY_ON_ARRAY_OR_TUPLE);
+        }
+    } else if (!typeAnnotation->IsTSArrayType() && !typeAnnotation->IsETSTuple() &&
+               !(typeAnnotation->IsETSTypeReference() &&
+                 typeAnnotation->AsETSTypeReference()->BaseName()->Name() == compiler::Signatures::ARRAY)) {
         if (!ParseReadonlyInTypeAnnotation()) {
             LogError(diagnostic::READONLY_ONLY_ON_ARRAY_OR_TUPLE);
         } else {
             LogError(diagnostic::READONLY_TYPE_EXPECTED);
         }
     }
+
     typeAnnotation->SetStart(startPos);
     typeAnnotation->AddModifier(ir::ModifierFlags::READONLY_PARAMETER);
     return typeAnnotation;