diff --git a/template/calfbox/nullbox.py b/template/calfbox/nullbox.py
index 38302c4..8d8ce7e 100644
--- a/template/calfbox/nullbox.py
+++ b/template/calfbox/nullbox.py
@@ -1,18 +1,23 @@
+#! /usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+import importlib
+
 class NullCalfbox(str): #iterable
     """A drop-in replacement for calfboxs python module.
     Use this for testing and development.
 
     At the start of your program, first file, insert:
-        import nullbox
+        import prefix.calfbox.nullbox
      or
         from SOMETHING import nullbox
 
     All further
-        from calfbox import cbox
+        from prefix.calfbox import cbox
     will use the null module.
 
     Even additional
-        import calfbox
+        import prefix.calfbox
     will use the nullbox module.
     """
 
@@ -55,13 +60,28 @@ class NullCalfbox(str): #iterable
 
 
 import sys
-import nullbox
-#Hack 'from calfbox import cbox'
-sys.modules["calfbox"] = sys.modules["nullbox"]
-import calfbox
 
+try:
+    import nullbox
+except ModuleNotFoundError:
+    from . import nullbox
+
+for key, value in sys.modules.items():
+    if "nullbox" in key:
+        r = key
+        break
+else:
+    raise ValueError("Nullbox Module not found")
+
+#r is the actual name of the calfbox parent modul. We cannot assume it to be "calfbox".
+calfboxModuleName = r[:-len(".nullbox")] #remove suffix
+sys.modules[calfboxModuleName] = sys.modules[r] #e.g. sys.modules["calfbox"] is now nullbox
+
+#Hack 'from prefix.calfbox import cbox'
+importlib.import_module(calfboxModuleName) #Imported once here, all modules will import this variant later.
+#import calfbox
 cbox = NullCalfbox("fake cbox null client")
 
 #Hack direct call 'import cbox'
 sys.modules["cbox"] = cbox
-import cbox
+import cbox #Imported once here, all modules will import this variant later.
diff --git a/template/start.py b/template/start.py
index 6303112..7c73498 100644
--- a/template/start.py
+++ b/template/start.py
@@ -111,20 +111,11 @@ if compiledVersion:
         "desktopfile": os.path.join(prefix, "share", "applications", METADATA["shortName"] + ".desktop"), # type: ignore #not ~/Desktop  but our desktop file
         "share": os.path.join(prefix, "share", METADATA["shortName"]), # type: ignore
         "templateShare": os.path.join(prefix, "share", METADATA["shortName"], "template"), # type: ignore
-        #"lib": os.path.join(prefix, "lib", METADATA["shortName"]), #cbox is found via the PYTHONPATH
     }
 
     _root = os.path.dirname(__file__)
     _root = os.path.abspath(os.path.join(_root, ".."))
 
-    import zipfile
-    import tempfile
-    logger.info("Extracting shared library to temporary directory")
-    zipfilePath = get_script_dir().rstrip("/template")
-    assert zipfile.is_zipfile(zipfilePath), (zipfilePath) #in our tests this worked. but in lss this results not in a zip file header. linux file also says it is no zip. However, unzip works.
-    #Extract included .so to tmp dir, tmp dir gets garbage collected at the end of our program.
-    libsharedDir = tempfile.TemporaryDirectory()
-
 #Not compiled, not installed. Running pure python directly in the source tree.
 else:
     _root = os.path.dirname(__file__)
@@ -136,7 +127,6 @@ else:
         "desktopfile": os.path.join(_root, "desktop", "desktop.desktop"),  #not ~/Desktop  but our desktop file
         "share": os.path.join(_root, "engine", "resources"),
         "templateShare": os.path.join(_root, "template", "engine", "resources"),
-        #"lib": "", #use only system paths
     }
 
 logger.info("PATHS: {}".format(PATHS))
@@ -326,13 +316,9 @@ if args.mute:
     Needs adding of the local tree into python search path.
 
     4) impossible: run program installed, calfbox in local tree
-
     """
-    #if not compiledVersion:
-    #import template.calfbox.py
-    #    sys.modules["calfbox"] = sys.modules["template.calfbox.py"]
-
     import template.calfbox.nullbox
+    logger.info(f"Using {sys.modules['template.calfbox']} as calfbox/nullbox")
 else:
     import ctypes.util
     libname = ctypes.util.find_library("calfbox-lss") #returns something like 'libcalfbox-lss.so.1' without a path, but with "lib"