diff --git a/desc/magnetic_fields/_core.py b/desc/magnetic_fields/_core.py
index ab5f852bdc..760f4e372b 100644
--- a/desc/magnetic_fields/_core.py
+++ b/desc/magnetic_fields/_core.py
@@ -613,7 +613,7 @@ def save_mgrid(
         )
         bz_001[:] = B_Z
 
-        if A_R is not None:
+        if save_vector_potential:
             ar_001 = file.createVariable("ar_001", np.float64, ("phi", "zee", "rad"))
             ar_001.long_name = (
                 "A_R = radial component of magnetic vector potential "