diff --git a/runtime/ecma_string-inl.h b/runtime/ecma_string-inl.h
index cc4921026464b8ef9533e79bbf94fd63544409a8..1bff12ab0ddede2fcf57689c9ed4e812ec36ab00 100644
--- a/runtime/ecma_string-inl.h
+++ b/runtime/ecma_string-inl.h
@@ -142,7 +142,8 @@ void EcmaString::WriteData(EcmaString *src, uint32_t start, uint32_t destSize, u
         }
     } else {
         // NOLINTNEXTLINE(cppcoreguidelines-pro-bounds-pointer-arithmetic)
-        if (length != 0 && memcpy_s(GetDataUtf16Writable() + start, destSize, src->GetDataUtf16(), length) != EOK) {
+        if (length != 0 && memcpy_s(GetDataUtf16Writable() + start, ComputeDataSizeUtf16(destSize), src->GetDataUtf16(),
+                                    ComputeDataSizeUtf16(length)) != EOK) {
             LOG_ECMA(FATAL) << "memcpy_s failed";
             UNREACHABLE();
         }