diff --git a/mininet/test/test_walkthrough.py b/mininet/test/test_walkthrough.py
index 39be95f..2e01bdf 100755
--- a/mininet/test/test_walkthrough.py
+++ b/mininet/test/test_walkthrough.py
@@ -19,12 +19,13 @@ from mininet.clean import cleanup
 def tsharkVersion():
     "Return tshark version"
     versionStr = quietRun( 'tshark -v' )
-    versionMatch = re.findall( r'TShark[^\d]*(\d+.\d+.\d+)', versionStr )
-    return versionMatch[ 0 ]
+    versionMatch = re.findall( r'TShark[^\d]*(\d+\.\d+\.\d+)', versionStr )
+    return versionMatch[ 0 ] if versionMatch else '0.0.0'
 
 # pylint doesn't understand pexpect.match, unfortunately!
 # pylint:disable=maybe-no-member
 
+@unittest.skipIf( pexpect is None, 'pexpect is not installed' )
 class testWalkthrough( unittest.TestCase ):
     "Test Mininet walkthrough"
 
diff --git a/mininet/util.py b/mininet/util.py
index e776e9f..e3110bf 100644
--- a/mininet/util.py
+++ b/mininet/util.py
@@ -59,8 +59,53 @@ try:
     import packaging.version  # replacement for distutils.version
     StrictVersion = packaging.version.parse
 except ImportError:  # python2.7 lacks ModuleNotFoundError
-    import distutils.version  # pylint: disable=deprecated-module
-    StrictVersion = distutils.version.StrictVersion
+    try:
+        import distutils.version  # pylint: disable=deprecated-module
+        StrictVersion = distutils.version.StrictVersion
+    except ( ImportError, AttributeError ):
+        import re
+
+        class FallbackStrictVersion( object ):
+            "Fallback version comparator when packaging/distutils are unavailable"
+            def __init__( self, vstring=None ):
+                self.vstring = str( vstring ) if vstring is not None else ''
+                self.version = self._parse( self.vstring )
+
+            @staticmethod
+            def _parse( vstring ):
+                components = re.findall( r'\d+|\D+', vstring.strip() )
+                return tuple( int( c ) if c.isdigit() else c for c in components )
+
+            def __lt__( self, other ):
+                other_ver = other.version if isinstance( other, FallbackStrictVersion ) else self._parse( str( other ) )
+                return self.version < other_ver
+
+            def __le__( self, other ):
+                other_ver = other.version if isinstance( other, FallbackStrictVersion ) else self._parse( str( other ) )
+                return self.version <= other_ver
+
+            def __gt__( self, other ):
+                other_ver = other.version if isinstance( other, FallbackStrictVersion ) else self._parse( str( other ) )
+                return self.version > other_ver
+
+            def __ge__( self, other ):
+                other_ver = other.version if isinstance( other, FallbackStrictVersion ) else self._parse( str( other ) )
+                return self.version >= other_ver
+
+            def __eq__( self, other ):
+                other_ver = other.version if isinstance( other, FallbackStrictVersion ) else self._parse( str( other ) )
+                return self.version == other_ver
+
+            def __ne__( self, other ):
+                return not self.__eq__( other )
+
+            def __repr__( self ):
+                return "StrictVersion('%s')" % self.vstring
+
+            def __str__( self ):
+                return self.vstring
+
+        StrictVersion = FallbackStrictVersion
 
 try:
     oldpexpect = None
@@ -79,7 +124,7 @@ try:
             return getattr( oldpexpect, name )
     pexpect = Pexpect()
 except ImportError:
-    pass
+    pexpect = None
 
 
 # Command execution support
diff --git a/util/install.sh b/util/install.sh
index 60d7b64..00ee5e6 100755
--- a/util/install.sh
+++ b/util/install.sh
@@ -190,7 +190,7 @@ function mn_deps {
 
         $install gcc make socat psmisc xterm ssh iperf telnet \
                  ethtool help2man $pf pylint $pep8 \
-                 net-tools ${PYPKG}-tk
+                 net-tools ${PYPKG}-tk ${PYPKG}-packaging || true
 
         # Install pip
         $install ${PYPKG}-pip || $install ${PYPKG}-pip-whl
@@ -203,7 +203,7 @@ function mn_deps {
             sudo ${PYTHON} get-pip.py
             rm get-pip.py
         fi
-       ${python} -m pip install pexpect
+        ${PYTHON} -m pip install pexpect || true
         $install iproute2 || $install iproute
         $install cgroup-tools || $install cgroup-bin
         $install cgroupfs-mount
diff --git a/util/versioncheck.py b/util/versioncheck.py
index a9d6cfc..ddc69d5 100755
--- a/util/versioncheck.py
+++ b/util/versioncheck.py
@@ -13,7 +13,7 @@ version = 'Mininet ' + run( 'PYTHONPATH=. bin/mn --version 2>&1', shell=True )
 version = version.strip()
 
 # Find all Mininet path references
-lines = run( "egrep -or 'Mininet [0-9\.\+]+\w*' *", shell=True )
+lines = run( r"egrep -or 'Mininet [0-9\.\+]+\w*' *", shell=True )
 
 error = False