diff --git a/napalm_s350/s350.py b/napalm_s350/s350.py
index e2111fc..f6c77d7 100644
--- a/napalm_s350/s350.py
+++ b/napalm_s350/s350.py
@@ -89,6 +89,7 @@ def __init__(self, hostname, username, password, timeout=60, optional_args=None)
             except KeyError:
                 pass
 
+        self.platform = "s350"
         self.port = optional_args.get("port", 22)
         self.device = None
         self.force_no_enable = optional_args.get("force_no_enable", False)
@@ -366,7 +367,7 @@ def _get_facts_uptime(self, show_sys):
         return uptime_str
 
     def _get_facts_parse_inventory(self, show_inventory):
-        """ inventory can list more modules/devices """
+        """inventory can list more modules/devices"""
         # make 1 module 1 line
         show_inventory = re.sub(r"\nPID", "  PID", show_inventory, re.M)
         # delete empty lines
@@ -473,7 +474,7 @@ def get_interfaces(self):
                 entry = {
                     "is_up": is_up,
                     "is_enabled": is_enabled,
-                    "speed": speed,
+                    "speed": float(speed),
                     "mtu": mtu,
                     "last_flapped": -1.0,
                     "description": description,
@@ -525,7 +526,7 @@ def get_interfaces_ip(self):
         return interfaces
 
     def _get_ip_int_line_to_fields(self, line, fields_end):
-        """ dynamic fields lenghts """
+        """dynamic fields lenghts"""
         line_elems = {}
         index = 0
         f_start = 0
@@ -536,7 +537,7 @@ def _get_ip_int_line_to_fields(self, line, fields_end):
         return line_elems
 
     def _get_ip_int_fields_end(self, dashline):
-        """ fields length are diferent device to device, detect them on horizontal lin """
+        """fields length are diferent device to device, detect them on horizontal line"""
 
         fields_end = [m.start() for m in re.finditer(" ", dashline.strip())]
         # fields_position.insert(0,0)
@@ -590,7 +591,7 @@ def get_lldp_neighbors(self):
         return neighbors
 
     def _get_lldp_neighbors_line_to_fields(self, line, fields_end):
-        """ dynamic fields lenghts """
+        """dynamic fields lenghts"""
         line_elems = {}
         index = 0
         f_start = 0
@@ -601,7 +602,7 @@ def _get_lldp_neighbors_line_to_fields(self, line, fields_end):
         return line_elems
 
     def _get_lldp_neighbors_fields_end(self, dashline):
-        """ fields length are diferent device to device, detect them on horizontal lin """
+        """fields length are diferent device to device, detect them on horizontal line"""
 
         fields_end = [m.start() for m in re.finditer(" ", dashline)]
         fields_end.append(len(dashline))
diff --git a/requirements-dev.txt b/requirements-dev.txt
index becc136..69b67af 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -1,12 +1,14 @@
-black==20.8b1
-coveralls==2.1.2
-ddt==1.4.1
-flake8-import-order==0.18.1
-pytest==5.4.3
-pytest-cov==2.10.1
-pytest-json==0.4.0
-pytest-pythonpath==0.7.3
-pylama==7.7.1
-mock==4.0.2
-tox==3.20.1
-demjson
+napalm>=3.0.0, <4.0.0
+netmiko>=3.1.0, <4.0.0
+black
+coveralls
+ddt
+flake8-import-order
+pytest==6.2.5
+pytest-cov
+pytest-json
+pytest-pythonpath
+pylama
+pyflakes==2.4.0 #prevent problems
+mock
+tox
diff --git a/requirements.txt b/requirements.txt
index c17be3f..405545b 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,3 @@
-napalm>=3.0.0
-netmiko>=3.1.0
+napalm>=3.0.0, <4.0.0
+netmiko>=3.1.0, <4.0.0
 netaddr
diff --git a/test/unit/conftest.py b/test/unit/conftest.py
index 6f9fb30..bd99cb3 100644
--- a/test/unit/conftest.py
+++ b/test/unit/conftest.py
@@ -1,4 +1,5 @@
 """Test fixtures."""
+
 from builtins import super
 
 import pytest
diff --git a/test/unit/test_getters.py b/test/unit/test_getters.py
index 5f87d9e..e470888 100644
--- a/test/unit/test_getters.py
+++ b/test/unit/test_getters.py
@@ -1,4 +1,5 @@
 """Tests for getters."""
+
 from napalm.base.test.getters import BaseTestGetters
 import pytest
 
diff --git a/tox.ini b/tox.ini
index 55340d6..d6c5f93 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,6 @@
 [tox]
 #envlist = py3{6,7,8},black,pylama,sphinx
-envlist = py3{6,7,8},pylama,black
+envlist = py3{8,9,10,11,12},pylama,black
 skip_missing_interpreters = true
 
 [testenv]