diff --git a/src/python_st3215/decorators.py b/src/python_st3215/decorators.py
index 863f91e..925e30c 100644
--- a/src/python_st3215/decorators.py
+++ b/src/python_st3215/decorators.py
@@ -44,19 +44,19 @@ def wrapper(self: Any, value: int, *args: Any, **kwargs: Any) -> Any:
 def encode_signed_word(value: int) -> tuple[int, int]:
     """
     Encode a signed 16-bit value to low and high bytes.
+    Encoding uses most-significant bit as sign bit.
 
     Args:
-        value: Signed integer (-32768 to 32767)
+        value: Signed integer (-32767 to 32767)
 
     Returns:
         Tuple of (low_byte, high_byte)
     """
+    if value < -32767 or value > 32767:
+        raise ValueError
+    low, high = abs(value) & 0xFF, (abs(value) >> 8) & 0x7F
     if value < 0:
-        raw = 65536 + value
-    else:
-        raw = value
-    low = raw & 0xFF
-    high = (raw >> 8) & 0xFF
+        high |= 0x80
     return low, high
 
 
@@ -65,13 +65,13 @@ def decode_signed_word(raw: int) -> int:
     Decode a 16-bit raw value to signed integer.
 
     Args:
-        raw: Raw 16-bit value (0-65535)
+        raw: Raw 16-bit value (0-65535) with dedicated sign bit.
 
     Returns:
-        Signed integer (-32768 to 32767)
+        Signed integer (-32767 to 32767)
     """
     if raw & 0x8000:
-        return raw - 65536
+        return -(raw & 0x7FFF)
     return raw
 
 
diff --git a/src/python_st3215/registers.py b/src/python_st3215/registers.py
index 7809676..f13d193 100644
--- a/src/python_st3215/registers.py
+++ b/src/python_st3215/registers.py
@@ -1268,7 +1268,7 @@ def read_current_speed(self) -> Optional[int]:
         Returns:
             int: Current speed in steps/s.    Returns None if read fails.
         """
-        return read_word(self.servo, 0x3A)
+        return read_word(self.servo, 0x3A, signed=True)
 
     def sync_read_current_speed(self, servo_ids: list[int]) -> dict[int, Optional[int]]:
         """
@@ -1295,7 +1295,7 @@ def sync_read_current_speed(self, servo_ids: list[int]) -> dict[int, Optional[in
                     raw = data[0] | (data[1] << 8)
                 else:
                     raw = data[0] | (data[1] << 8)
-                results[servo_id] = raw
+                results[servo_id] = decode_signed_word(raw)
             else:
                 results[servo_id] = None
         return results
diff --git a/src/python_st3215/st3215.py b/src/python_st3215/st3215.py
index 4d25a1d..e29e358 100644
--- a/src/python_st3215/st3215.py
+++ b/src/python_st3215/st3215.py
@@ -447,20 +447,26 @@ def _sync_read(
         )
         parameters = [address, data_length, *servo_ids]
         packet = self.send_instruction(0xFE, Instruction.SYNC_READ, parameters)
-        responses: dict[int, Optional[dict[str, object]]] = {}
-        for servo_id in servo_ids:
-            response = self.read_response(packet)
-            if response:
-                parsed = self.parse_response(response)
-                self.logger.debug(
-                    f"Servo {servo_id}: received SYNC READ response {parsed}"
-                )
-                responses[servo_id] = parsed
-            else:
+        responses: dict[int, Optional[dict[str, object]]] = {
+                servo_id: None for servo_id in servo_ids
+        }
+        rx = self.read_response(packet)
+        if rx is None:
+            return responses
+        b = 0
+        while b+3 < len(rx) and rx[b]==0xFF and rx[b+1]==0xFF:
+            servo_id = rx[b+2]
+            paramlen = rx[b+3]
+            pkglen = paramlen + 4
+            if paramlen != data_length + 2:
                 self.logger.warning(
-                    f"Servo {servo_id}: no response received for SYNC READ"
+                        f"Servo {servo_id}: no valid response for SYNC READ"
                 )
                 responses[servo_id] = None
+                break
+            if b+pkglen <= len(rx):
+                responses[servo_id] = self.parse_response(rx[b:b+pkglen])
+            b += pkglen
         return responses
 
     def __enter__(self) -> "ST3215":