diff --git a/src/Mod/Arch/importIFC.py b/src/Mod/Arch/importIFC.py
index e67611429..39d32045a 100644
--- a/src/Mod/Arch/importIFC.py
+++ b/src/Mod/Arch/importIFC.py
@@ -31,7 +31,9 @@ __url__ = "http://free-cad.sourceforge.net"
 DEBUG = True
 SCHEMA = "http://www.steptools.com/support/stdev_docs/express/ifc2x3/ifc2x3_tc1.exp"
 SKIP = ["IfcOpeningElement"]
-pyopen = open # because we'll redefine open below
+
+if open.__module__ == '__builtin__':
+    pyopen = open # because we'll redefine open below
 
 def open(filename):
     "called when freecad opens a file"
diff --git a/src/Mod/Arch/importOBJ.py b/src/Mod/Arch/importOBJ.py
index 4c452eb72..e5ddca434 100644
--- a/src/Mod/Arch/importOBJ.py
+++ b/src/Mod/Arch/importOBJ.py
@@ -24,7 +24,8 @@
 import FreeCAD
 from draftlibs import fcgeo
 
-pythonopen = open
+if open.__module__ == '__builtin__':
+    pythonopen = open
 
 def findVert(aVertex,aList):
     "finds aVertex in aList, returns index"