diff --git a/requirements.txt b/requirements.txt
index c8c85df..843e2c0 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -10,7 +10,7 @@ tqdm>=4.65.0
 plotly>=5.9.0
 numba>=0.57.1
 metpy>=1.5.1
-CosRayModifiedISO >= 1.2.3
+CosRayModifiedISO >= 1.2.9
 AsympDirsCalculator >= 1.0.8
 seaborn >= 0.13.2
 geopandas >= 0.11.1