diff --git a/requirements.txt b/requirements.txt
index ef8dd51..57eac0e 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
-netCDF4>=1.5.3
+netCDF4>=1.5.3,<=1.6.4
 ujson>=5.4.0
 numpy>=1.18.2
 numba>=0.54.0