diff --git a/Userland/Libraries/LibJS/Runtime/Intl/NumberFormat.cpp b/Userland/Libraries/LibJS/Runtime/Intl/NumberFormat.cpp
index bcb69eed40..8f8b3cc8e0 100644
--- a/Userland/Libraries/LibJS/Runtime/Intl/NumberFormat.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Intl/NumberFormat.cpp
@@ -215,6 +215,8 @@ void NumberFormatBase::set_rounding_mode(StringView rounding_mode)
         m_rounding_mode = RoundingMode::HalfTrunc;
     else if (rounding_mode == "trunc"sv)
         m_rounding_mode = RoundingMode::Trunc;
+    else
+        VERIFY_NOT_REACHED();
 }
 
 StringView NumberFormatBase::trailing_zero_display_string() const