diff --git a/mdahole2/analysis/hole.py b/mdahole2/analysis/hole.py
index 6d7f91e..a3cd41b 100644
--- a/mdahole2/analysis/hole.py
+++ b/mdahole2/analysis/hole.py
@@ -22,6 +22,7 @@
 #
 import os
 import errno
+import shutil
 import tempfile
 import textwrap
 import logging
@@ -217,7 +218,7 @@ def hole(pdbfile,
         warnings.warn(msg.format(output_level))
 
     # get executable
-    exe = util.which(executable)
+    exe = shutil.which(executable)
     if exe is None:
         raise OSError(errno.ENOENT, exe_err.format(name=executable,
                                                    kw='executable'))
@@ -500,23 +501,23 @@ def __init__(self, universe,
         self.ignore_residues = ignore_residues
 
         # --- finding executables ----
-        hole = util.which(executable)
+        hole = shutil.which(executable)
         if hole is None:
             raise OSError(errno.ENOENT, exe_err.format(name=executable,
                                                        kw='executable'))
         self.base_path = os.path.dirname(hole)
 
-        sos_triangle_path = util.which(sos_triangle)
+        sos_triangle_path = shutil.which(sos_triangle)
         if sos_triangle_path is None:
             path = os.path.join(self.base_path, sos_triangle)
-            sos_triangle_path = util.which(path)
+            sos_triangle_path = shutil.which(path)
         if sos_triangle_path is None:
             raise OSError(errno.ENOENT, exe_err.format(name=sos_triangle,
                                                        kw='sos_triangle'))
-        sph_process_path = util.which(sph_process)
+        sph_process_path = shutil.which(sph_process)
         if sph_process_path is None:
             path = os.path.join(self.base_path, sph_process)
-            sph_process_path = util.which(path)
+            sph_process_path = shutil.which(path)
         if sph_process_path is None:
             raise OSError(errno.ENOENT, exe_err.format(name=sph_process,
                                                        kw='sph_process'))