diff --git a/Userland/Libraries/LibWeb/Streams/UnderlyingSource.cpp b/Userland/Libraries/LibWeb/Streams/UnderlyingSource.cpp
index 27caa53435..45e68750ea 100644
--- a/Userland/Libraries/LibWeb/Streams/UnderlyingSource.cpp
+++ b/Userland/Libraries/LibWeb/Streams/UnderlyingSource.cpp
@@ -26,13 +26,13 @@ JS::ThrowCompletionOr<UnderlyingSource> UnderlyingSource::from_value(JS::VM& vm,
         .auto_allocate_chunk_size = {},
     };
 
-    if (TRY(object.has_property("type"))) {
-        auto type_value = TRY(TRY(object.get("type")).to_string(vm));
-        if (type_value == "bytes"sv) {
+    auto type_value = TRY(object.get("type"));
+    if (!type_value.is_undefined()) {
+        auto type_string = TRY(type_value.to_string(vm));
+        if (type_string == "bytes"sv)
             underlying_source.type = ReadableStreamType::Bytes;
-        } else {
+        else
             return vm.throw_completion<JS::TypeError>(DeprecatedString::formatted("Unknown stream type '{}'", type_value));
-        }
     }
 
     if (TRY(object.has_property("autoAllocateChunkSize")))