diff --git a/lhcbnightlyconf/Gauss.py b/lhcbnightlyconf/Gauss.py
index d03ecaee4240ee14262af246f17ea39aa7dccc41..35c7f936db125913bb06e0e381f7bde49175158e 100644
--- a/lhcbnightlyconf/Gauss.py
+++ b/lhcbnightlyconf/Gauss.py
@@ -334,11 +334,22 @@ gaussinoFastSim = create_gaussino_slot(
     'lhcb-gaussino-fastsim',
     'Test build of Fast Simulation Interface in Gaussino and Gauss-on-Gaussino',
 )
-for project in gaussinoFastSim.activeProjects:
-    if project.name not in ['PARAM', 'DBASE', 'Gaussino', 'Gauss']:
-        project.checkout_opts['merges'] = ['all', 'label=lhcb-gaussino']
 gaussinoFastSim.cache_entries['GEANT4FILES_VERSION'] = 'v107r0'
 gaussinoFastSim.cache_entries['GEANT4_TAG'] = 'lhcb/v10.7.0-branch'
+gaussinoFastSim.Gaussino.version = 'FASTSIM'
+gaussinoFastSim.Gaussino.checkout_opts = {
+    'merges': [
+        # 'all', disabled on purpose
+        'label=lhcb-gaussino-fastsim',
+    ],
+}
+gaussinoFastSim.Gauss.version = 'FASTSIM'
+gaussinoFastSim.Gauss.checkout_opts = {
+    'merges': [
+        # 'all', disabled on purpose
+        'label=lhcb-gaussino-fastsim',
+    ],
+}
 slots.append(gaussinoFastSim)
 
 # Slot for Gaussino with the new CMake