diff --git a/afl_transforms/tools/zax/critical_edge_breaker.hpp b/afl_transforms/tools/zax/critical_edge_breaker.hpp
index 68715523b0fc5945ab7d20da62dba70c62fac489..bbeeebcdd1e2f5ddb5b29b55ef4651dbbbd1bb7c 100644
--- a/afl_transforms/tools/zax/critical_edge_breaker.hpp
+++ b/afl_transforms/tools/zax/critical_edge_breaker.hpp
@@ -13,7 +13,7 @@ namespace Zafl
 	class CriticalEdgeBreaker_t
 	{
 		public:
-			CriticalEdgeBreaker_t(FileIR_t *p_variantIR, set<string> p_blacklist, const bool p_verbose=false);
+			CriticalEdgeBreaker_t(FileIR_t *p_variantIR, set<string> p_blacklist=set<string>(), const bool p_verbose=false);
 			unsigned getNumberExtraNodes() const;
 
 		protected: