diff --git a/octoprint_firmwareupdater/__init__.py b/octoprint_firmwareupdater/__init__.py
index 4ff24cd..c7cea2c 100644
--- a/octoprint_firmwareupdater/__init__.py
+++ b/octoprint_firmwareupdater/__init__.py
@@ -361,6 +361,7 @@ def __init__(self, reason, *args, **kwargs):
 		self.reason = reason
 
 __plugin_name__ = "Firmware Updater"
+__plugin_pythoncompat__ = ">=2.7,<4"
 
 def __plugin_load__():
 	global __plugin_implementation__
diff --git a/octoprint_firmwareupdater/methods/avrdude.py b/octoprint_firmwareupdater/methods/avrdude.py
index f49a28e..3dddb6f 100644
--- a/octoprint_firmwareupdater/methods/avrdude.py
+++ b/octoprint_firmwareupdater/methods/avrdude.py
@@ -83,11 +83,11 @@ def _flash_avrdude(self, firmware=None, printer_port=None):
     self._console_logger.info(u"")
     self._console_logger.info(avrdude_command)
     try:
-        p = sarge.run(avrdude_command, cwd=working_dir, async=True, stdout=sarge.Capture(), stderr=sarge.Capture())
+        p = sarge.run(avrdude_command, cwd=working_dir, async_=True, stdout=sarge.Capture(), stderr=sarge.Capture())
         p.wait_events()
 
         while p.returncode is None:
-            output = p.stderr.read(timeout=0.5)
+            output = p.stderr.read(timeout=0.5).decode('utf-8')
             if not output:
                 p.commands[0].poll()
                 continue
diff --git a/octoprint_firmwareupdater/methods/bossac.py b/octoprint_firmwareupdater/methods/bossac.py
index 177e272..3758294 100644
--- a/octoprint_firmwareupdater/methods/bossac.py
+++ b/octoprint_firmwareupdater/methods/bossac.py
@@ -61,11 +61,11 @@ def _flash_bossac(self, firmware=None, printer_port=None):
     self._console_logger.info(u"")
     self._console_logger.info(bossac_command)
     try:
-        p = sarge.run(bossac_command, cwd=working_dir, async=True, stdout=sarge.Capture(buffer_size=1), stderr=sarge.Capture(buffer_size=1))
+        p = sarge.run(bossac_command, cwd=working_dir, async_=True, stdout=sarge.Capture(buffer_size=1), stderr=sarge.Capture(buffer_size=1))
         p.wait_events()
 
         while p.returncode is None:
-            output = p.stdout.read(timeout=0.5)
+            output = p.stdout.read(timeout=0.5).decode('utf-8')
             if not output:
                 p.commands[0].poll()
                 continue
@@ -90,7 +90,7 @@ def _flash_bossac(self, firmware=None, printer_port=None):
         if p.returncode == 0:
             return True
         else:
-            output = p.stderr.read(timeout=0.5)
+            output = p.stderr.read(timeout=0.5).decode('utf-8')
             for line in output.split("\n"):
                 if line.endswith("\r"):
                     line = line[:-1]
diff --git a/octoprint_firmwareupdater/methods/dfuprog.py b/octoprint_firmwareupdater/methods/dfuprog.py
index 7a2db95..013833d 100644
--- a/octoprint_firmwareupdater/methods/dfuprog.py
+++ b/octoprint_firmwareupdater/methods/dfuprog.py
@@ -50,11 +50,11 @@ def _flash_dfuprog(self, firmware=None, printer_port=None):
     self._send_status("progress", subtype="writing")
     self._console_logger.info(dfuprog_command)
     try:
-        p = sarge.run(dfuprog_command, cwd=working_dir, async=True, stdout=sarge.Capture(buffer_size=1), stderr=sarge.Capture(buffer_size=1))
+        p = sarge.run(dfuprog_command, cwd=working_dir, async_=True, stdout=sarge.Capture(buffer_size=1), stderr=sarge.Capture(buffer_size=1))
         p.wait_events()
 
         while p.returncode is None:
-            output = p.stderr.read(timeout=0.5)
+            output = p.stderr.read(timeout=0.5).decode('utf-8')
             if not output:
                 p.commands[0].poll()
                 continue
@@ -100,11 +100,11 @@ def _erase_dfuprog(self):
     self._logger.info(u"Running '{}' in {}".format(dfuprog_erasecommand, working_dir))
     self._console_logger.info(dfuprog_erasecommand)
     try:
-        p = sarge.run(dfuprog_erasecommand, cwd=working_dir, async=True, stdout=sarge.Capture(buffer_size=1), stderr=sarge.Capture(buffer_size=1))
+        p = sarge.run(dfuprog_erasecommand, cwd=working_dir, async_=True, stdout=sarge.Capture(buffer_size=1), stderr=sarge.Capture(buffer_size=1))
         p.wait_events()
 
         while p.returncode is None:
-            output = p.stderr.read(timeout=0.5)
+            output = p.stderr.read(timeout=0.5).decode('utf-8')
             if not output:
                 p.commands[0].poll()
                 continue
diff --git a/octoprint_firmwareupdater/methods/stm32flash.py b/octoprint_firmwareupdater/methods/stm32flash.py
index 6baea23..208b5ac 100644
--- a/octoprint_firmwareupdater/methods/stm32flash.py
+++ b/octoprint_firmwareupdater/methods/stm32flash.py
@@ -74,11 +74,11 @@ def _flash_stm32flash(self, firmware=None, printer_port=None):
     self._console_logger.info(stm32flash_command)
 
     try:
-        p = sarge.run(stm32flash_command, cwd=working_dir, async=True, stdout=sarge.Capture(), stderr=sarge.Capture())
+        p = sarge.run(stm32flash_command, cwd=working_dir, async_=True, stdout=sarge.Capture(), stderr=sarge.Capture())
         p.wait_events()
 
         while p.returncode is None:
-            output = p.stdout.read(timeout=0.5)
+            output = p.stdout.read(timeout=0.5).decode('utf-8')
             if not output:
                 p.commands[0].poll()
                 continue
@@ -95,7 +95,7 @@ def _flash_stm32flash(self, firmware=None, printer_port=None):
         if p.returncode == 0:
             return True
         else:
-            output = p.stderr.read(timeout=0.5)
+            output = p.stderr.read(timeout=0.5).decode('utf-8')
             for line in output.split("\n"):
                 if line.endswith("\r"):
                     line = line[:-1]