diff --git a/src/io.py b/src/io.py
index 42853f5..a4f46b4 100644
--- a/src/io.py
+++ b/src/io.py
@@ -498,6 +498,9 @@ def __do_interp_lon_1D(self, dirs, fns, cnt_lon, lon_cnt, n_col, lon_idx_rng):
 
                 new_lon = np.linspace(new_min, new_max, new_sz)
 
+                merit_dat.close()
+                rema_dat.close()
+
                 return new_lon