diff --git a/certbot/tests/util_test.py b/certbot/tests/util_test.py
index 866f71e3d..cd02d835d 100644
--- a/certbot/tests/util_test.py
+++ b/certbot/tests/util_test.py
@@ -45,19 +45,34 @@ class RunScriptTest(unittest.TestCase):
         self.assertRaises(errors.SubprocessError, self._call, ["test"])
 
 
-class WhichTest(unittest.TestCase):
-    @mock.patch('certbot.util._is_exe')
-    def test_which(self, mock_is_exe):
-        from certbot.util import which
-        mock_is_exe.return_value = True
-        self.assertEqual(which("/path/to/something"), "/path/to/something")
+class ExeExistsTest(unittest.TestCase):
+    """Tests for certbot.util.exe_exists."""
 
-        with mock.patch.dict('os.environ', {"PATH": "/floop:/fleep"}):
-            mock_is_exe.return_value = True
-            self.assertEqual(which("pingify"), "/floop/pingify")
-            mock_is_exe.return_value = False
-            self.assertEqual(which("pingify"), None)
-        self.assertEqual(which("/path/to/something"), None)
+    @classmethod
+    def _call(cls, exe):
+        from certbot.util import exe_exists
+        return exe_exists(exe)
+
+    @mock.patch("certbot.util.os.path.isfile")
+    @mock.patch("certbot.util.os.access")
+    def test_full_path(self, mock_access, mock_isfile):
+        mock_access.return_value = True
+        mock_isfile.return_value = True
+        self.assertTrue(self._call("/path/to/exe"))
+
+    @mock.patch("certbot.util.os.path.isfile")
+    @mock.patch("certbot.util.os.access")
+    def test_on_path(self, mock_access, mock_isfile):
+        mock_access.return_value = True
+        mock_isfile.return_value = True
+        self.assertTrue(self._call("exe"))
+
+    @mock.patch("certbot.util.os.path.isfile")
+    @mock.patch("certbot.util.os.access")
+    def test_not_found(self, mock_access, mock_isfile):
+        mock_access.return_value = False
+        mock_isfile.return_value = True
+        self.assertFalse(self._call("exe"))
 
 
 class MakeOrVerifyDirTest(unittest.TestCase):
diff --git a/certbot/util.py b/certbot/util.py
index 733b3e501..cc0a74bd2 100644
--- a/certbot/util.py
+++ b/certbot/util.py
@@ -68,36 +68,28 @@ def run_script(params, log=logger.error):
     return stdout, stderr
 
 
-def _is_exe(fpath):
-    return os.path.isfile(fpath) and os.access(fpath, os.X_OK)
-
-def which(program):
+def exe_exists(exe):
     """Determine whether path/name refers to an executable.
 
-    :param str program: Executable path or name
+    :param str exe: Executable path or name
 
-    :returns: Path to executable if it exists, or None
-    :rtype: str or None
+    :returns: If exe is a valid executable
+    :rtype: bool
 
     """
-    # Borrowed from:
-    # https://stackoverflow.com/questions/377017/test-if-executable-exists-in-python
-    # XXX May need more porting to handle .exe extensions on Windows
+    def is_exe(path):
+        """Determine if path is an exe."""
+        return os.path.isfile(path) and os.access(path, os.X_OK)
 
-    fpath, _fname = os.path.split(program)
-    if fpath:
-        if _is_exe(program):
-            return program
+    path, _ = os.path.split(exe)
+    if path:
+        return is_exe(exe)
     else:
         for path in os.environ["PATH"].split(os.pathsep):
-            exe_file = os.path.join(path, program)
-            if _is_exe(exe_file):
-                return exe_file
+            if is_exe(os.path.join(path, exe)):
+                return True
 
-    return None
-
-# Either name makes sense, and we have a lot of call sites!
-exe_exists = which
+    return False
 
 
 def make_or_verify_dir(directory, mode=0o755, uid=0, strict=False):