diff --git a/test/test_ctatools.sh b/test/test_ctatools.sh
index 75331ab..8fa0985 100755
--- a/test/test_ctatools.sh
+++ b/test/test_ctatools.sh
@@ -2,6 +2,11 @@
 #
 # ctatools test script
 # ====================================================================
+PFILES=$PWD/../src/ctobssim
+PFILES=$PWD/../src/ctbin:$PFILES
+PFILES=$PWD/../src/ctselect:$PFILES
+PFILES=$PWD/../src/ctlike:$PFILES
+export PFILES
 
 #
 # Print Header
diff --git a/test/test_python.py b/test/test_python.py
index 344ba94..6be98ce 100755
--- a/test/test_python.py
+++ b/test/test_python.py
@@ -168,6 +168,13 @@ if __name__ == '__main__':
 	print "* ctatools Python interface testing *"
 	print "************************************"
 	
+	# Set PFILES environment variable
+	pfiles  = "../src/ctobssim:"
+	pfiles += "../src/ctbin:"
+	pfiles += "../src/ctselect:"
+	pfiles += "../src/ctlike:"
+	os.environ['PFILES'] = pfiles
+	
 	# Remove any existing result files
 	list = [glob.glob("*.fits"), glob.glob("*.log"), glob.glob("*.xml")]
 	for files in list: