diff --git a/tests/libfuzzer/corelib/time/qdatetime/fromstring/main.cpp b/tests/libfuzzer/corelib/time/qdatetime/fromstring/main.cpp
index 688bd3c24b8..ba1ddb081f4 100644
--- a/tests/libfuzzer/corelib/time/qdatetime/fromstring/main.cpp
+++ b/tests/libfuzzer/corelib/time/qdatetime/fromstring/main.cpp
@@ -35,6 +35,7 @@
 #endif
 
 static const QString formats[] = {
+    QStringLiteral("M/d/yyyy"),
     QStringLiteral("h"),
     QStringLiteral("hh"),
     QStringLiteral("H"),
@@ -47,7 +48,6 @@ static const QString formats[] = {
     QStringLiteral("zzz"),
     QStringLiteral("A"),
     QStringLiteral("t"),
-    QStringLiteral("M/d/yyyy"),
     QStringLiteral("M/d/yyyy hh:mm"),
     QStringLiteral("M/d/yyyy hh:mm A"),
     QStringLiteral("M/d/yyyy, hh:mm"),
@@ -99,6 +99,10 @@ extern "C" int LLVMFuzzerTestOneInput(const char *Data, size_t Size)
     QDateTime::fromString(userString, Qt::RFC2822Date);
     QDateTime::fromString(userString, Qt::ISODateWithMs);
 
+    QDateTime::fromString(userString, formats[0], QCalendar(QCalendar::System::Gregorian));
+    for (int sys = int(QCalendar::System::Julian); sys <= int(QCalendar::System::Last); ++sys)
+        QDateTime::fromString(userString, formats[0], QCalendar(sys));
+
     for (const auto &format : formats) {
         #ifdef LOG_FORMAT
         qDebug() << "Trying format:" << format;