diff --git a/lslopt/lslbasefuncs.py b/lslopt/lslbasefuncs.py
index e1cae4c..fce3f03 100644
--- a/lslopt/lslbasefuncs.py
+++ b/lslopt/lslbasefuncs.py
@@ -1982,3 +1982,5 @@ def llXorBase64StringsCorrect(s, xor):
         if xor[i] == b'\x00':
             i = 0
     return b64encode(ret).decode('utf8')
+
+lslbasefuncs_used = True
diff --git a/lslopt/lslcommon.py b/lslopt/lslcommon.py
index 4f45604..a59ca77 100644
--- a/lslopt/lslcommon.py
+++ b/lslopt/lslcommon.py
@@ -19,6 +19,7 @@
 
 import sys
 from strutil import *
+strutil_used
 
 _exclusions = frozenset(('nt','t','name','value','ch', 'X','SEF'))
 
diff --git a/lslopt/lslfuncs.py b/lslopt/lslfuncs.py
index 2263512..7b00eaa 100644
--- a/lslopt/lslfuncs.py
+++ b/lslopt/lslfuncs.py
@@ -20,3 +20,4 @@
 from lslopt.lslbasefuncs import *
 from lslopt.lsljson import *
 from lslopt.lslextrafuncs import *
+lslbasefuncs_used
diff --git a/lslopt/lslparse.py b/lslopt/lslparse.py
index faf87a7..b3303ff 100644
--- a/lslopt/lslparse.py
+++ b/lslopt/lslparse.py
@@ -23,6 +23,7 @@
 from lslopt.lslcommon import Key, Vector, Quaternion, types, nr
 from lslopt import lslcommon, lslfuncs
 from strutil import *
+strutil_used
 import re
 
 # Note this module was basically written from bottom to top, which may help
diff --git a/run-tests.py b/run-tests.py
index 096616d..75c8cce 100755
--- a/run-tests.py
+++ b/run-tests.py
@@ -56,7 +56,7 @@ try:
     import difflib
 except ImportError:
     difflib = None
-if sys.hexversion < 0x3000000:
+if sys.version_info.major < 3:
     from StringIO import StringIO as StringStream
 else:
     from io import BytesIO as StringStream
diff --git a/strutil.py b/strutil.py
index ee464c9..cd8b020 100644
--- a/strutil.py
+++ b/strutil.py
@@ -22,7 +22,7 @@ import codecs
 codecs.register(lambda x: codecs.lookup('utf8') if x == 'cp65001' else None)
 
 import sys
-if sys.hexversion >= 0x3000000:
+if sys.version_info.major >= 3:
     unicode = str
     unichr = chr
     def str2u(s, enc=None):
@@ -87,3 +87,5 @@ def werr(s):
 def wout(s):
     """Write any string to stdout"""
     sys.stdout.write(any2u(s, sys.stdout))
+
+strutil_used = True