diff --git a/src/opds_dumper.cpp b/src/opds_dumper.cpp
index af642246c..91bfb7f44 100644
--- a/src/opds_dumper.cpp
+++ b/src/opds_dumper.cpp
@@ -73,9 +73,6 @@ IllustrationInfo getBookIllustrationInfo(const Book& book)
 kainjow::mustache::object getSingleBookData(const Book& book)
 {
     const auto bookDate = book.getDate() + "T00:00:00Z";
-    const MustacheData bookUrl = book.getUrl().empty()
-                               ? MustacheData(false)
-                               : MustacheData(book.getUrl());
     return kainjow::mustache::object{
       {"id", book.getId()},
       {"name", book.getName()},
@@ -92,7 +89,7 @@ kainjow::mustache::object getSingleBookData(const Book& book)
       {"media_count", to_string(book.getMediaCount())},
       {"author_name", book.getCreator()},
       {"publisher_name", book.getPublisher()},
-      {"url", bookUrl},
+      {"url", onlyAsNonEmptyMustacheValue(book.getUrl())},
       {"size", to_string(book.getSize())},
       {"icons", getBookIllustrationInfo(book)},
     };
@@ -194,7 +191,7 @@ string OPDSDumper::dumpOPDSFeed(const std::vector<std::string>& bookIds, const s
      {"date", gen_date_str()},
      {"root", rootLocation},
      {"feed_id", gen_uuid(libraryId + "/catalog/search?"+query)},
-     {"filter", query.empty() ? MustacheData(false) : MustacheData(query)},
+     {"filter", onlyAsNonEmptyMustacheValue(query)},
      {"totalResults", to_string(m_totalResults)},
      {"startIndex", to_string(m_startIndex)},
      {"itemsPerPage", to_string(m_count)},
@@ -214,7 +211,7 @@ string OPDSDumper::dumpOPDSFeedV2(const std::vector<std::string>& bookIds, const
      {"date", gen_date_str()},
      {"endpoint_root", endpointRoot},
      {"feed_id", gen_uuid(libraryId + endpoint + "?" + query)},
-     {"filter", query.empty() ? MustacheData(false) : MustacheData(query)},
+     {"filter", onlyAsNonEmptyMustacheValue(query)},
      {"query", query.empty() ? "" : "?" + urlEncode(query)},
      {"totalResults", to_string(m_totalResults)},
      {"startIndex", to_string(m_startIndex)},
diff --git a/src/tools/otherTools.cpp b/src/tools/otherTools.cpp
index 1afcc7d7b..ab5bf5874 100644
--- a/src/tools/otherTools.cpp
+++ b/src/tools/otherTools.cpp
@@ -370,6 +370,13 @@ std::string kiwix::gen_uuid(const std::string& s)
   return kiwix::to_string(zim::Uuid::generate(s));
 }
 
+kainjow::mustache::data kiwix::onlyAsNonEmptyMustacheValue(const std::string& s)
+{
+  return s.empty()
+       ? kainjow::mustache::data(false)
+       : kainjow::mustache::data(s);
+}
+
 std::string kiwix::render_template(const std::string& template_str, kainjow::mustache::data data)
 {
   kainjow::mustache::mustache tmpl(template_str);
diff --git a/src/tools/otherTools.h b/src/tools/otherTools.h
index 219332cdb..b1297798e 100644
--- a/src/tools/otherTools.h
+++ b/src/tools/otherTools.h
@@ -48,6 +48,10 @@ namespace kiwix
   std::string gen_date_str();
   std::string gen_uuid(const std::string& s);
 
+  // if s is empty then returns kainjow::mustache::data(false)
+  // otherwise kainjow::mustache::data(value)
+  kainjow::mustache::data onlyAsNonEmptyMustacheValue(const std::string& s);
+
   std::string render_template(const std::string& template_str, kainjow::mustache::data data);
 }