diff --git a/CEP/Pipeline/test/pipeline_test.run b/CEP/Pipeline/test/pipeline_test.run
index b45415ea964963bc2129d952e86ed8eabf73da0a..0d5427a0b7aca66ba42fc4defca8389788c60718 100755
--- a/CEP/Pipeline/test/pipeline_test.run
+++ b/CEP/Pipeline/test/pipeline_test.run
@@ -8,8 +8,8 @@
 #run the actual python script performing the tests
 # Run all test collected in the current directory (including possible self tests!)
 
-PYTHONPATH=${srcdir}/test_framework/fixture:${PYTHONPATH}
-export PYTHONPATH
+# The support tests need a lot of open files
+ulimit -n 2048
 
 python ${srcdir}/test_framework/unittest_runner.py -x results.xml -p ${srcdir}
 
diff --git a/CEP/Pipeline/test/test_framework/unittest_runner.py b/CEP/Pipeline/test/test_framework/unittest_runner.py
index ae60665e7bce5d84de9f512bb6b85c2f437e7f79..96be94dffe78f97be40074046166fb7bb8cd67b9 100644
--- a/CEP/Pipeline/test/test_framework/unittest_runner.py
+++ b/CEP/Pipeline/test/test_framework/unittest_runner.py
@@ -6,6 +6,11 @@ import inspect
 import sys
 import re
 
+# We need the fixture to be in the front of the python path.
+# Some packages (f.e. casacore) have a site.py, which get run at python start, and can modify
+# the python path. We thus can only prepend the fixture after python has started.
+sys.path=["%s/fixture" % os.path.dirname(__file__)] + sys.path
+
 class Discover():
     """
     Discover class collects all unit test case in <path> and recursive directories