diff --git a/src/corelib/text/qbytearray.h b/src/corelib/text/qbytearray.h
index 5902b015167..bf3327b9f95 100644
--- a/src/corelib/text/qbytearray.h
+++ b/src/corelib/text/qbytearray.h
@@ -308,7 +308,8 @@ public:
     QByteArray &assign(InputIterator first, InputIterator last)
     {
         d.assign(first, last);
-        d.data()[d.size] = '\0';
+        if (d.data())
+            d.data()[d.size] = '\0';
         return *this;
     }
 
diff --git a/tests/auto/corelib/text/qbytearray/tst_qbytearray.cpp b/tests/auto/corelib/text/qbytearray/tst_qbytearray.cpp
index 81d79da38b3..fea603faed7 100644
--- a/tests/auto/corelib/text/qbytearray/tst_qbytearray.cpp
+++ b/tests/auto/corelib/text/qbytearray/tst_qbytearray.cpp
@@ -1017,6 +1017,11 @@ void tst_QByteArray::assign()
         QByteArrayView test;
 
         QList<char> l = {'\0', 'T', 'E', 'S', 'T'};
+
+        ba.assign(l.begin(), l.begin());
+        QVERIFY(ba.isEmpty());
+        QCOMPARE(*ba.constData(), '\0');
+
         ba.assign(l.begin(), l.end());
         test = "\0TEST"_ba;
         QCOMPARE(ba, test);
@@ -1033,6 +1038,10 @@ void tst_QByteArray::assign()
         test = "T\0ST"_ba;
         QCOMPARE(ba, test);
         QCOMPARE(ba.size(), test.size());
+
+        ba.assign(l.begin(), l.begin());
+        QVERIFY(ba.isEmpty());
+        QCOMPARE(*ba.constData(), '\0');
     }
     // Test chaining
     {