diff --git a/modules/amv/caliop_clavrx_amv.py b/modules/amv/caliop_clavrx_amv.py
index c7e3a4fa755a5df0a2fa0ab8c521c311181eb219..7cbe64f00c7768a1d931e009ff3765f200e5ecbc 100644
--- a/modules/amv/caliop_clavrx_amv.py
+++ b/modules/amv/caliop_clavrx_amv.py
@@ -424,7 +424,7 @@ def compute_and_add_geo_hgt(path_to_amvs, path_to_gfs, amv_source, band='14', ou
         dims = ['num_amvs', 'num_params']
         amvs_da = xr.DataArray(amvs_nd, coords=coords, dims=dims)
         new_amv_fname = os.path.split(fname)[1]
-        new_amv_fname = os.path.splitext(new_amv_fname)[0] + 'nc4'
+        new_amv_fname = os.path.splitext(new_amv_fname)[0] + '.nc4'
         amvs_da.to_netcdf(new_amv_fname, format='NETCDF4')
 
         new_amv_fname = os.path.split(fname)[1]