diff --git a/guaCalc_huangjijingshi.py b/guaCalc_huangjijingshi.py
index 086136f..5152b44 100644
--- a/guaCalc_huangjijingshi.py
+++ b/guaCalc_huangjijingshi.py
@@ -77,7 +77,7 @@ def guaCalc_huangjijingshi(Map64Gua, Map24Jieqi, kDate):
     
     # Calculate hour gua (4-hour blocks)
     Gua24Hours = bianyao_huangjijingshi(Map64Gua, Gua1Day['yaoAll'])
-    k1 = min(int(np.ceil(kDate.hour / 4)), len(Gua24Hours) - 1)
+    k1 = min(int(np.floor(kDate.hour / 4)), len(Gua24Hours) - 1)
     Gua4Hour = Gua24Hours.iloc[[k1 + 1]].copy()
     Gua4Hour['Type'] = 'hour'