diff --git a/src/gsiqt/qt4/QtNetwork/QtNetwork.pro b/src/gsiqt/qt4/QtNetwork/QtNetwork.pro
index 58544eafb..00b0983f4 100644
--- a/src/gsiqt/qt4/QtNetwork/QtNetwork.pro
+++ b/src/gsiqt/qt4/QtNetwork/QtNetwork.pro
@@ -12,6 +12,9 @@ DEPENDPATH += $$TL_INC $$GSI_INC $$QTBASIC_INC
 
 LIBS += -L$$DESTDIR -lklayout_tl -lklayout_gsi -lklayout_qtbasic
 
+# because QQbject is used as base class for many classes, we need this:
+LIBS += -lklayout_QtCore
+
 SOURCES += \
   gsiDeclQtNetworkAdd.cc
 
diff --git a/src/gsiqt/qt4/QtNetwork/gsiDeclQtNetworkAdd.cc b/src/gsiqt/qt4/QtNetwork/gsiDeclQtNetworkAdd.cc
index 25f7c5097..a79a54d26 100644
--- a/src/gsiqt/qt4/QtNetwork/gsiDeclQtNetworkAdd.cc
+++ b/src/gsiqt/qt4/QtNetwork/gsiDeclQtNetworkAdd.cc
@@ -20,7 +20,6 @@
 
 */
 
-
 #include "gsiQt.h"
 
 #include <QPair>
diff --git a/src/gsiqt/qt4/QtSql/QtSql.pro b/src/gsiqt/qt4/QtSql/QtSql.pro
index 663f99b2b..c74889559 100644
--- a/src/gsiqt/qt4/QtSql/QtSql.pro
+++ b/src/gsiqt/qt4/QtSql/QtSql.pro
@@ -12,6 +12,9 @@ DEPENDPATH += $$TL_INC $$GSI_INC $$QTBASIC_INC
 
 LIBS += -L$$DESTDIR -lklayout_tl -lklayout_gsi -lklayout_qtbasic
 
+# because QAsbtractTableModel is used as base class, we need this:
+LIBS += -lklayout_QtCore
+
 SOURCES += \
 
 HEADERS += \
diff --git a/src/gsiqt/qt4/qt4.pro b/src/gsiqt/qt4/qt4.pro
index 01daec72f..36c09917d 100644
--- a/src/gsiqt/qt4/qt4.pro
+++ b/src/gsiqt/qt4/qt4.pro
@@ -9,8 +9,8 @@ SUBDIRS = \
   QtNetwork \
   QtDesigner
 
-# This is weired, but true: because QSignalMapper (inside QtCore) has a QWidget
-# argument, we need to enforce linking of QtCore against QtGui so this GSI declaration
-# is available there
-# TODO:
-QtCore.depends += QtGui
+QtGui.depends += QtCore
+QtNetwork.depends += QtCore
+QtSql.depends += QtCore
+QtDesigner.depends += QtCore
+QtXml.depends += QtCore
diff --git a/src/pya/pya/pya.cc b/src/pya/pya/pya.cc
index 0668299ba..7956d8813 100644
--- a/src/pya/pya/pya.cc
+++ b/src/pya/pya/pya.cc
@@ -2280,13 +2280,13 @@ PythonModule::init (const char *mod_name, const char *description)
   module = Py_InitModule3 (m_mod_name.c_str (), module_methods, m_mod_description.c_str ());
 #else
 
-  static struct PyModuleDef mod_def = {
+  struct PyModuleDef mod_def = {
      PyModuleDef_HEAD_INIT,
      m_mod_name.c_str (),
      NULL,     // module documentation
      -1,       // size of per-interpreter state of the module,
                // if the module keeps state in global variables.
-     module_methods
+     NULL
   };
 
   tl_assert (! mp_mod_def);
diff --git a/src/pymod/QtCore/QtCore.pro b/src/pymod/QtCore/QtCore.pro
index 40caf843a..b45334bd4 100644
--- a/src/pymod/QtCore/QtCore.pro
+++ b/src/pymod/QtCore/QtCore.pro
@@ -8,4 +8,8 @@ SOURCES = \
 
 HEADERS += \
 
-LIBS += -lklayout_QtCore -lklayout_QtGui -lklayout_QtWidgets
+LIBS += -lklayout_QtCore -lklayout_QtGui
+
+equals(HAVE_QT5, "1") {
+  LIBS += -lklayout_QtWidgets
+}
diff --git a/src/pymod/QtXml/QtXml.pro b/src/pymod/QtXml/QtXml.pro
index 532447f86..a8641948a 100644
--- a/src/pymod/QtXml/QtXml.pro
+++ b/src/pymod/QtXml/QtXml.pro
@@ -11,4 +11,8 @@ HEADERS += \
 LIBS += -lklayout_QtCore -lklayout_QtXml
 
 # Because of stupid dependency of QtCore on QtGui and this on QtWidgets:
-LIBS += -lklayout_QtGui -lklayout_QtWidgets
+LIBS += -lklayout_QtGui
+
+equals(HAVE_QT5, "1") {
+  LIBS += -lklayout_QtWidgets
+}
diff --git a/testdata/pymod/import_QtDesigner.py b/testdata/pymod/import_QtDesigner.py
index f8c491cda..314250d74 100644
--- a/testdata/pymod/import_QtDesigner.py
+++ b/testdata/pymod/import_QtDesigner.py
@@ -29,6 +29,7 @@ class BasicTest(unittest.TestCase):
     self.assertEqual("QFormBuilder" in QtDesigner.__all__, True)
 
   def test_2(self):
+    app = QtCore.QCoreApplication([ "appname" ])
     q = QtDesigner.QFormBuilder()
 
 # run unit tests
diff --git a/testdata/pymod/import_lay.py b/testdata/pymod/import_lay.py
index 4433624bd..ed877c03a 100644
--- a/testdata/pymod/import_lay.py
+++ b/testdata/pymod/import_lay.py
@@ -18,7 +18,8 @@
 
 import pykl.QtCore
 import pykl.QtGui
-import pykl.QtWidgets
+if not "QApplication" in pykl.QtGui.__all__:
+  import pykl.QtWidgets  # Qt5
 import pykl.lay as lay
 import unittest
 import sys