diff --git a/src/Mod/BIM/nativeifc/ifc_classification.py b/src/Mod/BIM/nativeifc/ifc_classification.py
index 0115ebe865..18de9a170f 100644
--- a/src/Mod/BIM/nativeifc/ifc_classification.py
+++ b/src/Mod/BIM/nativeifc/ifc_classification.py
@@ -21,7 +21,7 @@
 # ***************************************************************************
 
 
-from nativeifc import ifc_tools  # lazy import
+from . import ifc_tools  # lazy import
 
 
 def edit_classification(obj):
diff --git a/src/Mod/BIM/nativeifc/ifc_commands.py b/src/Mod/BIM/nativeifc/ifc_commands.py
index 2fb24fcf30..25591cdc01 100644
--- a/src/Mod/BIM/nativeifc/ifc_commands.py
+++ b/src/Mod/BIM/nativeifc/ifc_commands.py
@@ -25,7 +25,7 @@
 
 import FreeCAD
 import FreeCADGui
-from nativeifc import ifc_openshell
+from . import ifc_openshell
 
 translate = FreeCAD.Qt.translate
 QT_TRANSLATE_NOOP = FreeCAD.Qt.QT_TRANSLATE_NOOP
@@ -34,7 +34,7 @@ QT_TRANSLATE_NOOP = FreeCAD.Qt.QT_TRANSLATE_NOOP
 def get_project():
     """Gets the current project"""
 
-    from nativeifc import ifc_tools
+    from . import ifc_tools
 
     if FreeCADGui.Selection.getSelection():
         return ifc_tools.get_project(FreeCADGui.Selection.getSelection()[0])
@@ -57,7 +57,7 @@ class IFC_Diff:
         }
 
     def Activated(self):
-        from nativeifc import ifc_diff
+        from . import ifc_diff
 
         proj = get_project()
         if proj:
@@ -88,8 +88,8 @@ class IFC_Expand:
                         no = obj.ViewObject.Proxy.expandChildren(obj)
                         ns.extend(no)
         else:
-            from nativeifc import ifc_generator
-            from nativeifc import ifc_tools
+            from . import ifc_generator
+            from . import ifc_tools
 
             document = FreeCAD.ActiveDocument
             ifc_generator.delete_ghost(document)
@@ -130,7 +130,7 @@ class IFC_ConvertDocument:
                 translate("BIM", "The active document is already an IFC document")
             )
         else:
-            from nativeifc import ifc_tools
+            from . import ifc_tools
 
             ifc_tools.convert_document(doc)
 
@@ -154,7 +154,7 @@ class IFC_MakeProject:
 
     def Activated(self):
         from importers import exportIFC  # lazy loading
-        from nativeifc import ifc_tools
+        from . import ifc_tools
         from PySide import QtCore, QtGui
 
         doc = FreeCAD.ActiveDocument
@@ -196,7 +196,7 @@ class IFC_Save:
         return False
 
     def Activated(self):
-        from nativeifc import ifc_tools  # lazy loading
+        from . import ifc_tools  # lazy loading
 
         doc = FreeCAD.ActiveDocument
         if getattr(doc, "IfcFilePath", None):
@@ -231,8 +231,8 @@ class IFC_SaveAs:
         return False
 
     def Activated(self):
-        from nativeifc import ifc_tools  # lazy loading
-        from nativeifc import ifc_viewproviders
+        from . import ifc_tools  # lazy loading
+        from . import ifc_viewproviders
 
         doc = FreeCAD.ActiveDocument
         if ifc_viewproviders.get_filepath(doc):
diff --git a/src/Mod/BIM/nativeifc/ifc_diff.py b/src/Mod/BIM/nativeifc/ifc_diff.py
index 2becf39d02..43cf4822be 100644
--- a/src/Mod/BIM/nativeifc/ifc_diff.py
+++ b/src/Mod/BIM/nativeifc/ifc_diff.py
@@ -26,7 +26,7 @@ import difflib
 import FreeCAD
 import FreeCADGui
 import ifcopenshell
-from nativeifc import ifc_tools
+from . import ifc_tools
 import Arch_rc
 
 translate = FreeCAD.Qt.translate
diff --git a/src/Mod/BIM/nativeifc/ifc_export.py b/src/Mod/BIM/nativeifc/ifc_export.py
index ba81c6d5fd..91001de2df 100644
--- a/src/Mod/BIM/nativeifc/ifc_export.py
+++ b/src/Mod/BIM/nativeifc/ifc_export.py
@@ -30,8 +30,8 @@ from importers import exportIFC
 from importers import exportIFCHelper
 from importers import importIFCHelper
 
-from nativeifc import ifc_tools
-from nativeifc import ifc_import
+from . import ifc_tools
+from . import ifc_import
 
 
 PARAMS = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/NativeIFC")
diff --git a/src/Mod/BIM/nativeifc/ifc_generator.py b/src/Mod/BIM/nativeifc/ifc_generator.py
index 15731ec650..4c01bf2501 100644
--- a/src/Mod/BIM/nativeifc/ifc_generator.py
+++ b/src/Mod/BIM/nativeifc/ifc_generator.py
@@ -25,20 +25,23 @@ The only entry point in this module is the generate_geometry() function which is
 used by the execute() method of ifc_objects"""
 
 
-import time
 import re
 import FreeCAD
 from FreeCAD import Base
 import Part
+
 import ifcopenshell
-from ifcopenshell.util import element
-from nativeifc import ifc_tools
-from nativeifc import ifc_export
+import ifcopenshell.util.element
+
 import multiprocessing
+
 import FreeCADGui
+
 from pivy import coin
 from PySide import QtCore
 
+from . import ifc_tools
+from . import ifc_export
 
 def generate_geometry(obj, cached=False):
     """Sets the geometry of the given object from a corresponding IFC element.
diff --git a/src/Mod/BIM/nativeifc/ifc_geometry.py b/src/Mod/BIM/nativeifc/ifc_geometry.py
index 5257099c8c..1cdda68be9 100644
--- a/src/Mod/BIM/nativeifc/ifc_geometry.py
+++ b/src/Mod/BIM/nativeifc/ifc_geometry.py
@@ -22,11 +22,12 @@
 
 """This module contains geometry editing and geometry properties-related tools"""
 
-
 import FreeCAD
+
 import ifcopenshell
-from ifcopenshell.util import unit
-from nativeifc import ifc_tools
+import ifcopenshell.util.unit
+
+from . import ifc_tools
 
 
 def add_geom_properties(obj):
diff --git a/src/Mod/BIM/nativeifc/ifc_import.py b/src/Mod/BIM/nativeifc/ifc_import.py
index 007dfa3272..5a51801e28 100644
--- a/src/Mod/BIM/nativeifc/ifc_import.py
+++ b/src/Mod/BIM/nativeifc/ifc_import.py
@@ -20,20 +20,20 @@
 # *                                                                         *
 # ***************************************************************************
 
-import importlib
 import os
 import time
 
 import FreeCAD
-from nativeifc import ifc_tools
-from nativeifc import ifc_psets
-from nativeifc import ifc_materials
-from nativeifc import ifc_layers
-from nativeifc import ifc_status
+
+from . import ifc_tools
+from . import ifc_psets
+from . import ifc_materials
+from . import ifc_layers
+from . import ifc_status
 
 if FreeCAD.GuiUp:
     import FreeCADGui
-    import Arch_rc
+    import Arch_rc  # needed to load the Arch icons, noqa: F401
 
 
 PARAMS = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/NativeIFC")
@@ -79,7 +79,7 @@ def insert(
     stime = time.time()
     try:
         document = FreeCAD.getDocument(docname)
-    except:
+    except NameError:
         document = FreeCAD.newDocument()
     if singledoc is None:
         singledoc = PARAMS.GetBool("SingleDoc", True)
@@ -145,7 +145,6 @@ def get_options(strategy=None, shapemode=None, switchwb=None, silent=False):
     ask = PARAMS.GetBool("AskAgain", False)
     if ask and FreeCAD.GuiUp:
         import FreeCADGui
-        from PySide import QtGui
 
         dlg = FreeCADGui.PySideUic.loadUi(":/ui/dialogImport.ui")
         dlg.checkSwitchWB.hide()  # TODO see what to do with this...
@@ -188,7 +187,6 @@ def get_project_type(silent=False):
         return ptype
     if ask and FreeCAD.GuiUp:
         import FreeCADGui
-        from PySide import QtGui
 
         dlg = FreeCADGui.PySideUic.loadUi(":/ui/dialogCreateProject.ui")
         result = dlg.exec_()
@@ -202,16 +200,15 @@ def get_project_type(silent=False):
 # convenience functions
 
 def toggle_lock_on():
-
     ifc_status.on_toggle_lock(True, noconvert=True, setchecked=True)
 
-def toggle_lock_off():
 
+def toggle_lock_off():
     ifc_status.on_toggle_lock(False, noconvert=True, setchecked=True)
 
-def unset_modified():
 
+def unset_modified():
     try:
         FreeCADGui.ActiveDocument.Modified = False
-    except:
+    except AttributeError:
         pass
diff --git a/src/Mod/BIM/nativeifc/ifc_layers.py b/src/Mod/BIM/nativeifc/ifc_layers.py
index 2ab4b5a82a..f4fa9ab0dc 100644
--- a/src/Mod/BIM/nativeifc/ifc_layers.py
+++ b/src/Mod/BIM/nativeifc/ifc_layers.py
@@ -23,11 +23,10 @@
 """This NativeIFC module deals with layers"""
 
 
-from nativeifc import ifc_tools
 import ifcopenshell
-from ifcopenshell import util
-from ifcopenshell.util import element
+import ifcopenshell.util.element
 
+from . import ifc_tools
 
 def load_layers(obj):
     """Loads all the layers of an IFC file"""
diff --git a/src/Mod/BIM/nativeifc/ifc_materials.py b/src/Mod/BIM/nativeifc/ifc_materials.py
index 2bffd72760..e925116a26 100644
--- a/src/Mod/BIM/nativeifc/ifc_materials.py
+++ b/src/Mod/BIM/nativeifc/ifc_materials.py
@@ -22,13 +22,12 @@
 
 """This NativeIFC module deals with materials"""
 
-
 import FreeCAD
-from nativeifc import ifc_tools
-import ifcopenshell
-from ifcopenshell import util
-from ifcopenshell.util import element
 
+import ifcopenshell
+import ifcopenshell.util.element
+
+from . import ifc_tools
 
 def create_material(element, parent, recursive=False):
     """Creates a material object in the given project or parent material"""
diff --git a/src/Mod/BIM/nativeifc/ifc_objects.py b/src/Mod/BIM/nativeifc/ifc_objects.py
index be202c7012..c3350dab3e 100644
--- a/src/Mod/BIM/nativeifc/ifc_objects.py
+++ b/src/Mod/BIM/nativeifc/ifc_objects.py
@@ -120,7 +120,7 @@ class ifc_object:
     def rebuild_classlist(self, obj, setprops=False):
         """rebuilds the list of Class enum property according to current class"""
 
-        from nativeifc import ifc_tools  # lazy import
+        from . import ifc_tools  # lazy import
 
         obj.Class = [obj.IfcClass]
         obj.Class = ifc_tools.get_ifc_classes(obj, obj.IfcClass)
@@ -144,7 +144,7 @@ class ifc_object:
         return None
 
     def execute(self, obj):
-        from nativeifc import ifc_generator  # lazy import
+        from . import ifc_generator  # lazy import
 
         if obj.isDerivedFrom("Part::Feature"):
             cached = getattr(self, "cached", False)
@@ -167,7 +167,7 @@ class ifc_object:
     def edit_attribute(self, obj, attribute, value=None):
         """Edits an attribute of an underlying IFC object"""
 
-        from nativeifc import ifc_tools  # lazy import
+        from . import ifc_tools  # lazy import
 
         if not value:
             value = obj.getPropertyByName(attribute)
@@ -182,8 +182,8 @@ class ifc_object:
     def edit_annotation(self, obj, attribute, value=None):
         """Edits an attribute of an underlying IFC annotation"""
 
-        from nativeifc import ifc_tools  # lazy import
-        from nativeifc import ifc_export
+        from . import ifc_tools  # lazy import
+        from . import ifc_export
 
         if not value:
             if hasattr(obj, attribute):
@@ -239,8 +239,8 @@ class ifc_object:
     def edit_geometry(self, obj, prop):
         """Edits a geometry property of an object"""
 
-        from nativeifc import ifc_geometry  # lazy loading
-        from nativeifc import ifc_tools  # lazy import
+        from . import ifc_geometry  # lazy loading
+        from . import ifc_tools  # lazy import
 
         result = ifc_geometry.set_geom_property(obj, prop)
         if result:
@@ -249,7 +249,7 @@ class ifc_object:
     def edit_schema(self, obj, schema):
         """Changes the schema of an IFC document"""
 
-        from nativeifc import ifc_tools  # lazy import
+        from . import ifc_tools  # lazy import
 
         ifcfile = ifc_tools.get_ifcfile(obj)
         if not ifcfile:
@@ -275,22 +275,22 @@ class ifc_object:
     def edit_placement(self, obj):
         """Syncs the internal IFC placement"""
 
-        from nativeifc import ifc_tools  # lazy import
+        from . import ifc_tools  # lazy import
 
         ifc_tools.set_placement(obj)
 
     def edit_pset(self, obj, prop):
         """Edits a Pset value"""
 
-        from nativeifc import ifc_psets  # lazy import
+        from . import ifc_psets  # lazy import
 
         ifc_psets.edit_pset(obj, prop)
 
     def edit_group(self, obj):
         """Edits the children list"""
 
-        from nativeifc import ifc_tools  # lazy import
-        from nativeifc import ifc_layers
+        from . import ifc_tools  # lazy import
+        from . import ifc_layers
 
         if obj.Class in [
             "IfcPresentationLayerAssignment",
@@ -321,7 +321,7 @@ class ifc_object:
     def edit_type(self, obj):
         """Edits the type of this object"""
 
-        from nativeifc import ifc_types  # lazy import
+        from . import ifc_types  # lazy import
 
         ifc_types.edit_type(obj)
 
@@ -332,7 +332,7 @@ class ifc_object:
     def get_section_data(self, obj):
         """Returns two things: a list of objects and a cut plane"""
 
-        from nativeifc import ifc_tools  # lazy import
+        from . import ifc_tools  # lazy import
         import Part
 
         if not obj.IfcClass == "IfcAnnotation":
@@ -375,7 +375,7 @@ class ifc_object:
     def edit_classification(self, obj):
         """Edits the classification of this object"""
 
-        from nativeifc import ifc_classification  # lazy loading
+        from . import ifc_classification  # lazy loading
 
         ifc_classification.edit_classification(obj)
 
diff --git a/src/Mod/BIM/nativeifc/ifc_observer.py b/src/Mod/BIM/nativeifc/ifc_observer.py
index 2aa933d905..f650c91101 100644
--- a/src/Mod/BIM/nativeifc/ifc_observer.py
+++ b/src/Mod/BIM/nativeifc/ifc_observer.py
@@ -23,7 +23,6 @@
 """Document observer to act on documents containing NativeIFC objects"""
 
 
-import os
 import FreeCAD
 
 params = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/NativeIFC")
@@ -67,7 +66,7 @@ class ifc_observer:
     def slotDeletedObject(self, obj):
         """Deletes the corresponding object in the IFC document"""
 
-        from nativeifc import ifc_tools  # lazy loading
+        from . import ifc_tools  # lazy loading
 
         proj = ifc_tools.get_project(obj)
         if not proj:
@@ -82,11 +81,10 @@ class ifc_observer:
         """Watch document IFC properties"""
 
         # only look at locked IFC documents
-        if not "IfcFilePath" in doc.PropertiesList:
+        if "IfcFilePath" not in doc.PropertiesList:
             return
 
-        from nativeifc import ifc_tools  # lazy import
-        from nativeifc import ifc_status
+        from . import ifc_tools  # lazy import
 
         if prop == "Schema":
             schema = doc.Schema
@@ -126,13 +124,13 @@ class ifc_observer:
     def slotActivateDocument(self, doc):
         """Check if we need to lock"""
 
-        from nativeifc import ifc_status
+        from . import ifc_status
 
         ifc_status.on_activate()
 
     def slotRemoveDynamicProperty(self, obj, prop):
 
-        from nativeifc import ifc_psets
+        from . import ifc_psets
         ifc_psets.remove_property(obj, prop)
 
     # implementation methods
@@ -164,8 +162,8 @@ class ifc_observer:
                     if obj.Modified:
                         projects.append(obj)
         if projects:
-            from nativeifc import ifc_tools  # lazy loading
-            from nativeifc import ifc_viewproviders
+            from . import ifc_tools  # lazy loading
+            from . import ifc_viewproviders
 
             ask = params.GetBool("AskBeforeSaving", True)
             if ask and FreeCAD.GuiUp:
@@ -208,8 +206,8 @@ class ifc_observer:
         or "IfcType" in obj.PropertiesList \
         or "CreateSpreadsheet" in obj.PropertiesList:
             FreeCAD.Console.PrintLog("Converting " + obj.Label + " to IFC\n")
-            from nativeifc import ifc_geometry  # lazy loading
-            from nativeifc import ifc_tools  # lazy loading
+            from . import ifc_geometry  # lazy loading
+            from . import ifc_tools  # lazy loading
 
             newobj = ifc_tools.aggregate(obj, doc)
             ifc_geometry.add_geom_properties(newobj)
diff --git a/src/Mod/BIM/nativeifc/ifc_performance_test.py b/src/Mod/BIM/nativeifc/ifc_performance_test.py
index 0e0b6ec049..7fb7740cd1 100644
--- a/src/Mod/BIM/nativeifc/ifc_performance_test.py
+++ b/src/Mod/BIM/nativeifc/ifc_performance_test.py
@@ -24,7 +24,7 @@ import os
 import time
 import FreeCAD
 import unittest
-from nativeifc import ifc_import
+from . import ifc_import
 
 
 FILES = [
diff --git a/src/Mod/BIM/nativeifc/ifc_psets.py b/src/Mod/BIM/nativeifc/ifc_psets.py
index 472a751e32..bc4d993690 100644
--- a/src/Mod/BIM/nativeifc/ifc_psets.py
+++ b/src/Mod/BIM/nativeifc/ifc_psets.py
@@ -25,8 +25,10 @@
 
 import os
 import re
+
 import FreeCAD
-from nativeifc import ifc_tools
+
+from . import ifc_tools
 
 translate = FreeCAD.Qt.translate
 
@@ -361,7 +363,7 @@ def read_properties_conversion():
 def remove_property(obj, prop):
     """Removes a custom property"""
 
-    from nativeifc import ifc_tools
+    from . import ifc_tools
     ifcfile = ifc_tools.get_ifcfile(obj)
     if not ifcfile:
         return
diff --git a/src/Mod/BIM/nativeifc/ifc_selftest.py b/src/Mod/BIM/nativeifc/ifc_selftest.py
index bad6568d12..25300dd909 100644
--- a/src/Mod/BIM/nativeifc/ifc_selftest.py
+++ b/src/Mod/BIM/nativeifc/ifc_selftest.py
@@ -29,14 +29,14 @@ import FreeCAD
 import Draft
 import Arch
 import unittest
-from nativeifc import ifc_import
-from nativeifc import ifc_tools
-from nativeifc import ifc_geometry
-from nativeifc import ifc_materials
-from nativeifc import ifc_layers
-from nativeifc import ifc_psets
-from nativeifc import ifc_objects
-from nativeifc import ifc_generator
+from . import ifc_import
+from . import ifc_tools
+from . import ifc_geometry
+from . import ifc_materials
+from . import ifc_layers
+from . import ifc_psets
+from . import ifc_objects
+from . import ifc_generator
 import ifcopenshell
 from ifcopenshell.util import element
 import difflib
@@ -301,7 +301,7 @@ class NativeIFCTest(unittest.TestCase):
         self.assertTrue(obj.Shape.Volume > 1500000, "ChangeGeometry failed")
 
     def test12_RemoveObject(self):
-        from nativeifc import ifc_observer
+        from . import ifc_observer
         ifc_observer.add_observer()
         FreeCAD.Console.PrintMessage("NativeIFC 12: Remove object...")
         clearObjects()
diff --git a/src/Mod/BIM/nativeifc/ifc_status.py b/src/Mod/BIM/nativeifc/ifc_status.py
index 14d36894e8..a75375b509 100644
--- a/src/Mod/BIM/nativeifc/ifc_status.py
+++ b/src/Mod/BIM/nativeifc/ifc_status.py
@@ -101,7 +101,7 @@ def on_add_property():
     if not sel:
         return
     from PySide import QtCore, QtGui  # lazy loading
-    from nativeifc import ifc_psets
+    from . import ifc_psets
     obj = sel[0]
     psets = list(set([obj.getGroupOfProperty(p) for p in obj.PropertiesList]))
     psets = [p for p in psets if p]
@@ -180,7 +180,7 @@ def on_add_pset():
     if not sel:
         return
     from PySide import QtCore, QtGui  # lazy loading
-    from nativeifc import ifc_psets
+    from . import ifc_psets
     obj = sel[0]
     mw = FreeCADGui.getMainWindow()
     # read standard psets
@@ -328,7 +328,7 @@ def set_button(checked=False, setchecked=False):
 def unlock_document():
     """Unlocks the active document"""
 
-    from nativeifc import ifc_tools  # lazy loading
+    from . import ifc_tools  # lazy loading
 
     doc = FreeCAD.ActiveDocument
     if not doc:
@@ -356,10 +356,10 @@ def unlock_document():
 def lock_document():
     """Locks the active document"""
 
-    from nativeifc import ifc_tools  # lazy loading
+    from . import ifc_tools  # lazy loading
     from importers import exportIFC
-    from nativeifc import ifc_geometry
-    from nativeifc import ifc_export
+    from . import ifc_geometry
+    from . import ifc_export
     from PySide import QtCore
 
     doc = FreeCAD.ActiveDocument
diff --git a/src/Mod/BIM/nativeifc/ifc_tools.py b/src/Mod/BIM/nativeifc/ifc_tools.py
index 27ac90e750..e48754a6c4 100644
--- a/src/Mod/BIM/nativeifc/ifc_tools.py
+++ b/src/Mod/BIM/nativeifc/ifc_tools.py
@@ -33,14 +33,13 @@ translate = FreeCAD.Qt.translate
 
 try:
     import ifcopenshell
-    from ifcopenshell import geom
-    from ifcopenshell import api
-    from ifcopenshell import template
-    from ifcopenshell.util import element
-    from ifcopenshell.util import attribute
-    from ifcopenshell.util import schema
-    from ifcopenshell.util import placement
-    from ifcopenshell.util import unit
+    import ifcopenshell.api
+    import ifcopenshell.geom
+    import ifcopenshell.util.attribute
+    import ifcopenshell.util.element
+    import ifcopenshell.util.placement
+    import ifcopenshell.util.schema
+    import ifcopenshell.util.unit
 except ImportError as e:
     import FreeCAD
     FreeCAD.Console.PrintError(
@@ -52,13 +51,13 @@ except ImportError as e:
     )
     raise e
 
-from nativeifc import ifc_objects
-from nativeifc import ifc_viewproviders
-from nativeifc import ifc_import
-from nativeifc import ifc_layers
-from nativeifc import ifc_status
-from nativeifc import ifc_export
-from nativeifc import ifc_psets
+from . import ifc_objects
+from . import ifc_viewproviders
+from . import ifc_import
+from . import ifc_layers
+from . import ifc_status
+from . import ifc_export
+from . import ifc_psets
 
 from draftviewproviders import view_layer
 import ArchBuildingPart
@@ -134,7 +133,7 @@ def convert_document(document, filename=None, shapemode=0, strategy=0, silent=Fa
                3 = no children
     """
 
-    if not "Proxy" in document.PropertiesList:
+    if "Proxy" not in document.PropertiesList:
         document.addProperty("App::PropertyPythonObject", "Proxy")
     document.setPropertyStatus("Proxy", "Transient")
     document.Proxy = ifc_objects.document_object()
@@ -161,9 +160,9 @@ def setup_project(proj, filename, shapemode, silent):
 
     full = False
     d = "The path to the linked IFC file"
-    if not "IfcFilePath" in proj.PropertiesList:
+    if "IfcFilePath" not in proj.PropertiesList:
         proj.addProperty("App::PropertyFile", "IfcFilePath", "Base", d)
-    if not "Modified" in proj.PropertiesList:
+    if "Modified" not in proj.PropertiesList:
         proj.addProperty("App::PropertyBool", "Modified", "Base")
     proj.setPropertyStatus("Modified", "Hidden")
     if filename:
@@ -181,7 +180,7 @@ def setup_project(proj, filename, shapemode, silent):
     # In IFC4, history is optional. What should we do here?
     proj.Proxy.ifcfile = ifcfile
     add_properties(proj, ifcfile, project, shapemode=shapemode)
-    if not "Schema" in proj.PropertiesList:
+    if "Schema" not in proj.PropertiesList:
         proj.addProperty("App::PropertyEnumeration", "Schema", "Base")
     # bug in FreeCAD - to avoid a crash, pre-populate the enum with one value
     proj.Schema = [ifcfile.wrapped_data.schema_name()]
@@ -321,7 +320,7 @@ def create_children(
     def create_child(parent, element):
         subresult = []
         # do not create if a child with same stepid already exists
-        if not element.id() in [
+        if element.id() not in [
             getattr(c, "StepId", 0) for c in get_parent_objects(parent)
         ]:
             doc = getattr(parent, "Document", parent)
@@ -1581,8 +1580,8 @@ def get_orphan_elements(ifcfile):
     ]
     # add control elements
     proj = ifcfile.by_type("IfcProject")[0]
-    for rel in proj.Declares:
-        for ctrl in getattr(rel,"RelatedDefinitions", []):
+    for rel in getattr(proj, "Declares", []):
+        for ctrl in getattr(rel, "RelatedDefinitions", []):
             if ctrl.is_a("IfcControl"):
                 products.append(ctrl)
     groups = []
@@ -1662,7 +1661,7 @@ def remove_tree(objs):
     nobjs = objs
     for obj in objs:
         for child in obj.OutListRecursive:
-            if not child in nobjs:
+            if child not in nobjs:
                 nobjs.append(child)
     deletelist = []
     for obj in nobjs:
diff --git a/src/Mod/BIM/nativeifc/ifc_tree.py b/src/Mod/BIM/nativeifc/ifc_tree.py
index cbfa923c8b..334e3e1931 100644
--- a/src/Mod/BIM/nativeifc/ifc_tree.py
+++ b/src/Mod/BIM/nativeifc/ifc_tree.py
@@ -79,7 +79,7 @@ def show_geometry_tree(element):
 
     import Arch_rc
     import FreeCADGui  # lazy import
-    from nativeifc import ifc_tools
+    from . import ifc_tools
     from PySide import QtGui, QtWidgets
 
     if isinstance(element, FreeCAD.DocumentObject):
@@ -146,7 +146,7 @@ def show_properties(current, previous):
     """Displays object properties"""
 
     import FreeCADGui
-    from nativeifc import ifc_tools  # lazy loading
+    from . import ifc_tools  # lazy loading
     from PySide import QtCore, QtGui, QtWidgets
 
     ifcid = int(current.text(0).split("=", 1)[0].strip(" ").strip("#"))
diff --git a/src/Mod/BIM/nativeifc/ifc_types.py b/src/Mod/BIM/nativeifc/ifc_types.py
index 0a714fa6d5..295d3cc8dd 100644
--- a/src/Mod/BIM/nativeifc/ifc_types.py
+++ b/src/Mod/BIM/nativeifc/ifc_types.py
@@ -24,7 +24,7 @@
 
 
 import FreeCAD
-from nativeifc import ifc_tools
+from . import ifc_tools
 
 translate = FreeCAD.Qt.translate
 
diff --git a/src/Mod/BIM/nativeifc/ifc_viewproviders.py b/src/Mod/BIM/nativeifc/ifc_viewproviders.py
index 3487c34460..13f0c6bd43 100644
--- a/src/Mod/BIM/nativeifc/ifc_viewproviders.py
+++ b/src/Mod/BIM/nativeifc/ifc_viewproviders.py
@@ -82,10 +82,10 @@ class ifc_vp_object:
         return []
 
     def setupContextMenu(self, vobj, menu):
-        from nativeifc import ifc_tools  # lazy import
-        from nativeifc import ifc_psets
-        from nativeifc import ifc_materials
-        from nativeifc import ifc_types
+        from . import ifc_tools  # lazy import
+        from . import ifc_psets
+        from . import ifc_materials
+        from . import ifc_types
         from PySide import QtCore, QtGui  # lazy import
 
         if FreeCADGui.activeWorkbench().name() != 'BIMWorkbench':
@@ -164,7 +164,7 @@ class ifc_vp_object:
     def hasChildren(self, obj):
         """Returns True if this IFC object can be decomposed"""
 
-        from nativeifc import ifc_tools  # lazy import
+        from . import ifc_tools  # lazy import
 
         ifcfile = ifc_tools.get_ifcfile(obj)
         if ifcfile:
@@ -174,7 +174,7 @@ class ifc_vp_object:
     def expandChildren(self, obj=None):
         """Creates children of this object"""
 
-        from nativeifc import ifc_tools  # lazy import
+        from . import ifc_tools  # lazy import
         from PySide import QtCore, QtGui
 
         if not obj:
@@ -260,14 +260,14 @@ class ifc_vp_object:
     def addGeometryProperties(self):
         """Adds geometry properties to this object"""
 
-        from nativeifc import ifc_geometry  # lazy loading
+        from . import ifc_geometry  # lazy loading
 
         ifc_geometry.add_geom_properties(self.Object)
 
     def addMaterial(self):
         """Adds a material to this object"""
 
-        from nativeifc import ifc_materials  # lazy loading
+        from . import ifc_materials  # lazy loading
 
         ifc_materials.show_material(self.Object)
         self.Object.Document.recompute()
@@ -275,8 +275,8 @@ class ifc_vp_object:
     def showTree(self):
         """Shows a dialog with a geometry tree for the object"""
 
-        from nativeifc import ifc_tools  # lazy loading
-        from nativeifc import ifc_tree  # lazy loading
+        from . import ifc_tools  # lazy loading
+        from . import ifc_tree  # lazy loading
 
         element = ifc_tools.get_ifc_element(self.Object)
         if element:
@@ -285,7 +285,7 @@ class ifc_vp_object:
     def showProps(self):
         """Expands property sets"""
 
-        from nativeifc import ifc_psets  # lazy loading
+        from . import ifc_psets  # lazy loading
 
         ifc_psets.show_psets(self.Object)
         self.Object.Document.recompute()
@@ -313,7 +313,7 @@ class ifc_vp_object:
     def dragObject(self, vobj, dragged_object):
         """Remove a child from the view provider by d&d"""
 
-        from nativeifc import ifc_tools  # lazy import
+        from . import ifc_tools  # lazy import
 
         parent = vobj.Object
         ifc_tools.deaggregate(dragged_object, parent)
@@ -329,7 +329,7 @@ class ifc_vp_object:
     def onDrop(self, incoming_object):
         """Delayed action to be taken when dropping an object"""
 
-        from nativeifc import ifc_tools  # lazy import
+        from . import ifc_tools  # lazy import
         ifc_tools.aggregate(incoming_object, self.Object)
         if self.hasChildren(self.Object):
             self.expandChildren(self.Object)
@@ -350,7 +350,7 @@ class ifc_vp_object:
     def createGroup(self):
         """Creates a group under this object"""
 
-        from nativeifc import ifc_tools  # lazy import
+        from . import ifc_tools  # lazy import
 
         group = self.Object.Document.addObject("App::DocumentObjectGroup", "Group")
         ifc_tools.aggregate(group, self.Object)
@@ -364,13 +364,13 @@ class ifc_vp_object:
     def expandProperties(self, vobj):
         """Expands everything that needs to be expanded"""
 
-        from nativeifc import ifc_geometry  # lazy import
-        from nativeifc import ifc_tools  # lazy import
-        from nativeifc import ifc_psets  # lazy import
-        from nativeifc import ifc_materials  # lazy import
-        from nativeifc import ifc_layers  # lazy import
-        from nativeifc import ifc_types  # lazy import
-        from nativeifc import ifc_classification  # lazy import
+        from . import ifc_geometry  # lazy import
+        from . import ifc_tools  # lazy import
+        from . import ifc_psets  # lazy import
+        from . import ifc_materials  # lazy import
+        from . import ifc_layers  # lazy import
+        from . import ifc_types  # lazy import
+        from . import ifc_classification  # lazy import
 
         # generic data loading
         ifc_geometry.add_geom_properties(vobj.Object)
@@ -399,7 +399,7 @@ class ifc_vp_object:
 
         if not hasattr(self, "Object"):
             return
-        from nativeifc import ifc_types
+        from . import ifc_types
         ifc_types.convert_to_type(self.Object)
         self.Object.Document.recompute()
 
@@ -444,7 +444,7 @@ class ifc_vp_document(ifc_vp_object):
     def save(self):
         """Saves the associated IFC file"""
 
-        from nativeifc import ifc_tools  # lazy import
+        from . import ifc_tools  # lazy import
 
         ifc_tools.save(self.Object)
         self.Object.Document.recompute()
@@ -452,7 +452,7 @@ class ifc_vp_document(ifc_vp_object):
     def saveas(self):
         """Saves the associated IFC file to another file"""
 
-        from nativeifc import ifc_tools  # lazy import
+        from . import ifc_tools  # lazy import
 
         sf = get_filepath(self.Object)
         if sf:
@@ -503,7 +503,7 @@ class ifc_vp_document(ifc_vp_object):
             return False
 
     def diff(self):
-        from nativeifc import ifc_diff
+        from . import ifc_diff
 
         diff = ifc_diff.get_diff(self.Object)
         ifc_diff.show_diff(diff)
@@ -600,8 +600,8 @@ class ifc_vp_material:
         return []
 
     def setupContextMenu(self, vobj, menu):
-        from nativeifc import ifc_tools  # lazy import
-        from nativeifc import ifc_psets
+        from . import ifc_tools  # lazy import
+        from . import ifc_psets
         from PySide import QtCore, QtGui  # lazy import
 
         if FreeCADGui.activeWorkbench().name() != 'BIMWorkbench':
@@ -616,7 +616,7 @@ class ifc_vp_material:
     def showProps(self):
         """Expands property sets"""
 
-        from nativeifc import ifc_psets  # lazy loading
+        from . import ifc_psets  # lazy loading
 
         ifc_psets.show_psets(self.Object)
         self.Object.Document.recompute()
@@ -659,7 +659,7 @@ def overlay(icon1, icon2):
 def get_filepath(project):
     """Saves the associated IFC file to another file"""
 
-    from nativeifc import ifc_tools  # lazy import
+    from . import ifc_tools  # lazy import
     from PySide import QtCore, QtGui  # lazy import
 
     sf = QtGui.QFileDialog.getSaveFileName(