diff --git a/Makefile b/Makefile
index a8274a649..c6b002a60 100644
--- a/Makefile
+++ b/Makefile
@@ -125,8 +125,8 @@ install-pip:  ## Install pip (no-op if already installed).
 setup-dev-env:  ## Install GIT hooks, pip, test deps (also upgrades them).
 	${MAKE} install-git-hooks
 	${MAKE} install-pip
-	$(PYTHON) -m pip install $(INSTALL_OPTS) --upgrade --trusted-host files.pythonhosted.org pip
-	$(PYTHON) -m pip install $(INSTALL_OPTS) --upgrade --trusted-host files.pythonhosted.org $(PY_DEPS)
+	$(PYTHON) -m pip install $(INSTALL_OPTS) --trusted-host files.pythonhosted.org --trusted-host pypi.org --upgrade pip
+	$(PYTHON) -m pip install $(INSTALL_OPTS) --trusted-host files.pythonhosted.org --trusted-host pypi.org --upgrade $(PY_DEPS)
 
 # ===================================================================
 # Tests
diff --git a/psutil/__init__.py b/psutil/__init__.py
index 68f3c7ca9..49ab94d50 100644
--- a/psutil/__init__.py
+++ b/psutil/__init__.py
@@ -404,7 +404,7 @@ def __str__(self):
                 pass
             if self._exitcode not in (_SENTINEL, None):
                 info["exitcode"] = self._exitcode
-            if self._create_time:
+            if self._create_time is not None:
                 info['started'] = _pprint_secs(self._create_time)
             return "%s.%s(%s)" % (
                 self.__class__.__module__,
@@ -418,6 +418,20 @@ def __eq__(self, other):
         # on PID and creation time.
         if not isinstance(other, Process):
             return NotImplemented
+        if OPENBSD or NETBSD:  # pragma: no cover
+            # Zombie processes on Open/NetBSD have a creation time of
+            # 0.0. This covers the case when a process started normally
+            # (so it has a ctime), then it turned into a zombie. It's
+            # important to do this because is_running() depends on
+            # __eq__.
+            pid1, ctime1 = self._ident
+            pid2, ctime2 = other._ident
+            if pid1 == pid2:
+                if ctime1 and not ctime2:
+                    try:
+                        return self.status() == STATUS_ZOMBIE
+                    except Error:
+                        pass
         return self._ident == other._ident
 
     def __ne__(self, other):
diff --git a/psutil/tests/__init__.py b/psutil/tests/__init__.py
index 1cb9fffde..62cef7633 100644
--- a/psutil/tests/__init__.py
+++ b/psutil/tests/__init__.py
@@ -43,6 +43,8 @@
 from psutil import AIX
 from psutil import LINUX
 from psutil import MACOS
+from psutil import NETBSD
+from psutil import OPENBSD
 from psutil import POSIX
 from psutil import SUNOS
 from psutil import WINDOWS
@@ -959,7 +961,12 @@ def assertProcessGone(self, proc):
 
     def assertProcessZombie(self, proc):
         # A zombie process should always be instantiable.
-        psutil.Process(proc.pid)
+        clone = psutil.Process(proc.pid)
+        # Cloned zombie on Open/NetBSD has null creation time, see:
+        # https://github.com/giampaolo/psutil/issues/2287
+        self.assertEqual(proc, clone)
+        if not (OPENBSD or NETBSD):
+            self.assertEqual(hash(proc), hash(clone))
         # Its status always be querable.
         self.assertEqual(proc.status(), psutil.STATUS_ZOMBIE)
         # It should be considered 'running'.
diff --git a/psutil/tests/test_system.py b/psutil/tests/test_system.py
index 9e81e2f5d..80e4988d5 100755
--- a/psutil/tests/test_system.py
+++ b/psutil/tests/test_system.py
@@ -72,6 +72,11 @@ def test_process_iter(self):
         p.wait()
         self.assertNotIn(sproc.pid, [x.pid for x in psutil.process_iter()])
 
+        # assert there are no duplicates
+        ls = [x for x in psutil.process_iter()]
+        self.assertEqual(sorted(ls, key=lambda x: x.pid),
+                         sorted(set(ls), key=lambda x: x.pid))
+
         with mock.patch('psutil.Process',
                         side_effect=psutil.NoSuchProcess(os.getpid())):
             self.assertEqual(list(psutil.process_iter()), [])