diff --git a/python/materials.py b/python/materials.py
index 604571494..ba7cb03b4 100644
--- a/python/materials.py
+++ b/python/materials.py
@@ -717,7 +717,11 @@
     ),
 ]
 
-Au_JC_visible = mp.Medium(epsilon=6.1599, E_susceptibilities=Au_JC_visible_susc)
+Au_JC_visible = mp.Medium(
+    epsilon=6.1599,
+    E_susceptibilities=Au_JC_visible_susc,
+    valid_freq_range=metal_visible_range,
+)
 
 # ------------------------------------------------------------------
 # gold (Au)