diff --git a/fast/diffusion_2D_wBCs.py b/fast/diffusion_2D_wBCs.py
index 8f0ddbdac7..0d117eee35 100644
--- a/fast/diffusion_2D_wBCs.py
+++ b/fast/diffusion_2D_wBCs.py
@@ -67,7 +67,7 @@
 if args.devito:
 
     # To measure Devito at its best on GPU, we have to set the tile siwe manually
-    opt = None
+    opt = 'advanced'
     if configuration['platform'].name == 'nvidiaX':
         opt = ('advanced', {'par-tile': (32, 4, 8)})
 
diff --git a/fast/diffusion_3D_wBCs.py b/fast/diffusion_3D_wBCs.py
index e93cc92e81..30e52bb055 100644
--- a/fast/diffusion_3D_wBCs.py
+++ b/fast/diffusion_3D_wBCs.py
@@ -61,7 +61,7 @@
     u.data[:, :, :, int(nz/2)] = 1
 
     # To measure Devito at its best on GPU, we have to set the tile siwe manually
-    opt = None
+    opt = 'advanced'
     if configuration['platform'].name == 'nvidiaX':
         opt = ('advanced', {'par-tile': (32, 4, 8)})
     op = Operator([eq_stencil], name='DevitoDiffusionOperator', opt=opt)