diff --git a/src/Trigger.cc b/src/Trigger.cc
index a567528232..ed5d0e18f6 100644
--- a/src/Trigger.cc
+++ b/src/Trigger.cc
@@ -44,7 +44,10 @@ TraversalCode TriggerTraversalCallback::PreExpr(const Expr* expr)
 		BroObj::SuppressErrors no_errors;
 		Val* v = e->Eval(trigger->frame);
 		if ( v )
+			{
 			trigger->Register(v);
+			Unref(v);
+			}
 		break;
 		}