diff --git a/ets2panda/checker/ETSAnalyzer.cpp b/ets2panda/checker/ETSAnalyzer.cpp
index 47e0797c65d9b1f4d5ea63ba08e3dac705a93c21..1f2d54eb0e5ae41c87b2e833f8a648092dc81030 100644
--- a/ets2panda/checker/ETSAnalyzer.cpp
+++ b/ets2panda/checker/ETSAnalyzer.cpp
@@ -1411,6 +1411,12 @@ Type *ETSAnalyzer::GetReturnType(ir::CallExpression *expr, Type *calleeType) con
         checker->ValidateSignatureAccessibility(calleeObj, signature, expr->Start());
     }
 
+    if (IsPromiseType(signature->ReturnType(), checker) && signature->HasFunction() &&
+        signature->Function()->Id()->Name().Is("then")) {
+        auto *newtype = UnwrapPromiseType(signature->ReturnType());
+        signature->SetReturnType(checker->CreatePromiseOf(newtype));
+    }
+
     expr->SetSignature(signature);
 
     // #22951: this type should not be encoded as a signature flag