diff --git a/src/prop/cadical.cpp b/src/prop/cadical.cpp
index 32397ce9155..420663f4695 100644
--- a/src/prop/cadical.cpp
+++ b/src/prop/cadical.cpp
@@ -663,6 +663,9 @@ class CadicalPropagator : public CaDiCaL::ExternalPropagator
         << " -> " << d_active_vars_control.size() << std::endl;
   }
 
+  /**
+   * Set the activation literal for the current user assertion level.
+   */
   void set_activation_lit(SatVariable& alit)
   {
     d_activation_literals.push_back(alit);