diff --git a/Trigger/TrigT1/L1Topo/L1TopoSimulation/CMakeLists.txt b/Trigger/TrigT1/L1Topo/L1TopoSimulation/CMakeLists.txt
index c9aab2bc2571b83596d506a1556da6af688a0d85..d59494a9456fba0a3be7143cd576cafee83cea52 100644
--- a/Trigger/TrigT1/L1Topo/L1TopoSimulation/CMakeLists.txt
+++ b/Trigger/TrigT1/L1Topo/L1TopoSimulation/CMakeLists.txt
@@ -33,7 +33,7 @@ atlas_disable_as_needed()
 
 # Component(s) in the package:
 atlas_add_library( L1TopoSimulationLib
-   L1TopoSimulation/*.h Root/*.cxx
+   L1TopoSimulation/*.h
    INTERFACE
    PUBLIC_HEADERS L1TopoSimulation
    LINK_LIBRARIES GaudiKernel )