diff --git a/src/corelib/tools/qstring.h b/src/corelib/tools/qstring.h
index bb918f36c8..8ce3d51b2c 100644
--- a/src/corelib/tools/qstring.h
+++ b/src/corelib/tools/qstring.h
@@ -534,11 +534,11 @@ public:
         return fromLocal8Bit_helper(str, (str && size == -1) ? int(strlen(str)) : size);
     }
     static inline QString fromLatin1(const QByteArray &str)
-    { return fromLatin1(str.data(), qstrnlen(str.constData(), str.size())); }
+    { return str.isNull() ? QString() : fromLatin1(str.data(), qstrnlen(str.constData(), str.size())); }
     static inline QString fromUtf8(const QByteArray &str)
-    { return fromUtf8(str.data(), qstrnlen(str.constData(), str.size())); }
+    { return str.isNull() ? QString() : fromUtf8(str.data(), qstrnlen(str.constData(), str.size())); }
     static inline QString fromLocal8Bit(const QByteArray &str)
-    { return fromLocal8Bit(str.data(), qstrnlen(str.constData(), str.size())); }
+    { return str.isNull() ? QString() : fromLocal8Bit(str.data(), qstrnlen(str.constData(), str.size())); }
     static QString fromUtf16(const ushort *, int size = -1);
     static QString fromUcs4(const uint *, int size = -1);
     static QString fromRawData(const QChar *, int size);
diff --git a/tests/auto/corelib/tools/qstring/tst_qstring.cpp b/tests/auto/corelib/tools/qstring/tst_qstring.cpp
index d2f7a6ee50..c3dbb26587 100644
--- a/tests/auto/corelib/tools/qstring/tst_qstring.cpp
+++ b/tests/auto/corelib/tools/qstring/tst_qstring.cpp
@@ -183,6 +183,7 @@ private slots:
     void fromLocal8Bit();
     void local8Bit_data();
     void local8Bit();
+    void nullFromLocal8Bit();
     void fromLatin1Roundtrip_data();
     void fromLatin1Roundtrip();
     void toLatin1Roundtrip_data();
@@ -3697,6 +3698,12 @@ void tst_QString::nullFromUtf8()
     a = QString::fromUtf8("");
     QVERIFY(!a.isNull());
     QVERIFY(a.isEmpty());
+    a = QString::fromUtf8(QByteArray());
+    QVERIFY(a.isNull());
+    QVERIFY(a.isEmpty());
+    a = QString::fromUtf8(QByteArray(""));
+    QVERIFY(!a.isNull());
+    QVERIFY(a.isEmpty());
 }
 
 void tst_QString::fromLocal8Bit_data()
@@ -3779,6 +3786,23 @@ void tst_QString::local8Bit()
     QCOMPARE(local8Bit.toLocal8Bit(), QByteArray(result));
 }
 
+void tst_QString::nullFromLocal8Bit()
+{
+    QString a;
+    a = QString::fromLocal8Bit(0);
+    QVERIFY(a.isNull());
+    QVERIFY(a.isEmpty());
+    a = QString::fromLocal8Bit("");
+    QVERIFY(!a.isNull());
+    QVERIFY(a.isEmpty());
+    a = QString::fromLocal8Bit(QByteArray());
+    QVERIFY(a.isNull());
+    QVERIFY(a.isEmpty());
+    a = QString::fromLocal8Bit(QByteArray(""));
+    QVERIFY(!a.isNull());
+    QVERIFY(a.isEmpty());
+}
+
 void tst_QString::stringRef_local8Bit_data()
 {
     local8Bit_data();
@@ -3945,6 +3969,12 @@ void tst_QString::fromLatin1()
     a = QString::fromLatin1( "" );
     QVERIFY( !a.isNull() );
     QVERIFY( a.isEmpty() );
+    a = QString::fromLatin1(QByteArray());
+    QVERIFY(a.isNull());
+    QVERIFY(a.isEmpty());
+    a = QString::fromLatin1(QByteArray(""));
+    QVERIFY(!a.isNull());
+    QVERIFY(a.isEmpty());
 
     a = QString::fromLatin1(0, 0);
     QVERIFY(a.isNull());