https://github.com/zeek/zeek/pull/3997

Index: src/DFA.h
--- src/DFA.h.orig
+++ src/DFA.h
@@ -70,7 +70,7 @@ class DFA_State : public Obj (protected)
 	DFA_State* mark;
 	};
 
-using DigestStr = std::basic_string<u_char>;
+using DigestStr = std::string;
 
 class DFA_State_Cache
 	{
