diff --git a/fiveparaminte-main/contec_parser.py b/fiveparaminte-main/contec_parser.py
index e301f81..966ebec 100644
--- a/fiveparaminte-main/contec_parser.py
+++ b/fiveparaminte-main/contec_parser.py
@@ -360,8 +360,8 @@ def _parse_288_byte_packet(data: bytes, vitals_dict: dict) -> bool:
     Parse 288-byte waveform packet (Subtype 21 for CMS8500).
     
     Layout:
+      [264-265] SpO2% (LE u16) — live oxygen saturation percentage
       [266-267] PR (LE u16) — pulse rate
-      [268-269] SpO2% (LE u16) — live oxygen saturation percentage
     """
     if len(data) < 270:
         return False
@@ -374,8 +374,8 @@ def _parse_288_byte_packet(data: bytes, vitals_dict: dict) -> bool:
 
     found = False
 
-    # Offset 268: SpO2 percentage
-    spo2_val = read_u16_le(data, 268)
+    # Offset 264: SpO2 percentage
+    spo2_val = read_u16_le(data, 264)
     if spo2_val is not None and spo2_val != 65535 and spo2_val != 255 and 50 <= spo2_val <= 100:
         vitals_dict["spo2"] = float(spo2_val)
         found = True