64 bits Linux compilation breaks due to QString initialized with int element

When in a 64 bits environment, numbers are treated as int instead of short. String has no int constructors, but have char, which match if passed as a short in 32 bits.

Error related:

g++ -c -pipe -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fstack-protector --param=ssp-buffer-size=4 -m64 -Wall -W -D_REENTRANT -fPIC -DPLUGIN_INTERNAL -DQT_NO_DEBUG -DQT_PLUGIN -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_CORE_LIB -I/usr/lib64/qt4/mkspecs/linux-g++ -I. -I/usr/include/QtCore -I/usr/include/QtNetwork -I/usr/include/QtGui -I/usr/include -I/usr/include/qmfutil -I/usr/include/messageserver -I/usr/include/qtopiamail -I. -I../../../libraries/qtopiamail -I../../../libraries/messageserver -I../../../libraries/qtopiamail/support -I../../../libraries/qmfutil -I. -I. -o imapclient.o imapclient.cpp
In file included from imapprotocol.h:45,
from imapclient.h:45,
from imapclient.cpp:42:
imapmailboxproperties.h: In constructor 'ImapMailboxProperties::ImapMailboxProperties(const QMailFolder&)':
imapmailboxproperties.h:59: error: call of overloaded 'QString(int)' is ambiguous
/usr/include/QtCore/qstring.h:427: note: candidates are: QString::QString(const QByteArray&)
/usr/include/QtCore/qstring.h:425: note: QString::QString(const char*)
/usr/include/QtCore/qstring.h:726: note: QString::QString(const QString&)
/usr/include/QtCore/qstring.h:106: note: QString::QString(QChar)
/usr/include/QtCore/qstring.h:105: note: QString::QString(const QChar*)
make[1]: *** [imapclient.o] Error 1

If is really necessary an initializer, is not better use QString::Null ?