diff --git a/ets2panda/compiler/lowering/ets/unboxLowering.cpp b/ets2panda/compiler/lowering/ets/unboxLowering.cpp
index 9826b156f30249cac42fb0f75a06c7223f92ea22..a2b945c3c4c08beba591bc25d678c72a6084eec3 100644
--- a/ets2panda/compiler/lowering/ets/unboxLowering.cpp
+++ b/ets2panda/compiler/lowering/ets/unboxLowering.cpp
@@ -485,12 +485,31 @@ static ir::Expression *InsertPrimitiveConversionIfNeeded(UnboxContext *uctx, ir:
             toConvert = tp;
         }
     };
-    checkSubtyping(checker->GlobalByteBuiltinType());
-    checkSubtyping(checker->GlobalShortBuiltinType());
-    checkSubtyping(checker->GlobalIntBuiltinType());
-    checkSubtyping(checker->GlobalLongBuiltinType());
-    checkSubtyping(checker->GlobalFloatBuiltinType());
-    checkSubtyping(checker->GlobalDoubleBuiltinType());
+
+    switch (checker->ETSType(MaybeRecursivelyUnboxType(uctx, actualType))) {
+        case checker::TypeFlag::BYTE:
+            checkSubtyping(checker->GlobalByteBuiltinType());
+            [[fallthrough]];
+        case checker::TypeFlag::SHORT:
+            checkSubtyping(checker->GlobalShortBuiltinType());
+            [[fallthrough]];
+        case checker::TypeFlag::CHAR:
+        case checker::TypeFlag::INT:
+            checkSubtyping(checker->GlobalIntBuiltinType());
+            [[fallthrough]];
+        case checker::TypeFlag::LONG:
+            checkSubtyping(checker->GlobalLongBuiltinType());
+            [[fallthrough]];
+        case checker::TypeFlag::FLOAT:
+            checkSubtyping(checker->GlobalFloatBuiltinType());
+            [[fallthrough]];
+        case checker::TypeFlag::DOUBLE:
+            checkSubtyping(checker->GlobalDoubleBuiltinType());
+            [[fallthrough]];
+        default:
+            break;
+    }
+
     if (toConvert == nullptr && actualType->IsCharType() &&
         relation->IsSupertypeOf(expectedType, checker->GlobalBuiltinETSStringType())) {
         toConvert = uctx->checker->GlobalBuiltinETSStringType();