diff --git a/scripts/pythonAPI/mycobot.py b/scripts/pythonAPI/mycobot.py
index 7360dda..06fba8d 100644
--- a/scripts/pythonAPI/mycobot.py
+++ b/scripts/pythonAPI/mycobot.py
@@ -94,7 +94,8 @@ class MyCobot():
 
         '''
         _hex = self._angle_to_hex(degree)
-        command = 'fefe0621{}{}{}fa'.format(id, _hex, hex(speed)[2:])
+        speed = self._complement_zero(hex(speed)[2:], digit=2)
+        command = 'fefe0621{}{}{}fa'.format(id, _hex, speed)
         # print(command)  
         self._write(command)
 
@@ -353,4 +354,4 @@ class MyCobot():
 
     def _read(self, size=1024):
         data = self.serial_port.read(size)
-        return data
\ No newline at end of file
+        return data
diff --git a/scripts/pythonAPI/mycobot3.py b/scripts/pythonAPI/mycobot3.py
index f6f8009..263386d 100644
--- a/scripts/pythonAPI/mycobot3.py
+++ b/scripts/pythonAPI/mycobot3.py
@@ -95,7 +95,8 @@ class MyCobot():
 
         '''
         _hex = self._angle_to_hex(degree)
-        command = 'fefe0621{}{}{}fa'.format(id, _hex, hex(speed)[2:])
+        speed = self._complement_zero(hex(speed)[2:], digit=2)
+        command = 'fefe0621{}{}{}fa'.format(id, _hex, speed)
         # print(command)  
         self._write(command)
 
@@ -354,4 +355,4 @@ class MyCobot():
 
     def _read(self, size: int=1024):
         data = self.serial_port.read(size)
-        return data
\ No newline at end of file
+        return data