diff --git a/smr/smr/assemblies.py b/smr/smr/assemblies.py
index dd71d97..aeba677 100644
--- a/smr/smr/assemblies.py
+++ b/smr/smr/assemblies.py
@@ -144,7 +144,7 @@ def assembly_universes(num_rings, num_axial, depleted):
     univs = {}
 
     # commonly needed universes
-    gtu = pins['GT empty']
+    gtu = pins['GT empty stack']
     gti = pins['GT empty instr']
     bas = pins['BA stack']
     ins = pins['IT stack']
diff --git a/smr/smr/pins.py b/smr/smr/pins.py
index 676fc8a..e71adf5 100644
--- a/smr/smr/pins.py
+++ b/smr/smr/pins.py
@@ -230,8 +230,8 @@ def pin_universes(num_rings=10, num_axial=196, depleted=False):
         surfs['top upper nozzle']
     ]
 
-    univs['GT empty'] = make_stack(
-        'GT empty', surfaces=stack_surfs,
+    univs['GT empty stack'] = make_stack(
+        'GT empty stack', surfaces=stack_surfs,
         universes=[univs['water pin'],
                    univs['water pin'],
                    univs['water pin'],