diff --git a/thirdparty/backward-cpp/backward.hpp b/thirdparty/backward-cpp/backward.hpp
index 839a56213..e2a22bc01 100644
--- a/thirdparty/backward-cpp/backward.hpp
+++ b/thirdparty/backward-cpp/backward.hpp
@@ -1879,7 +1879,6 @@ public:
 		SIGSEGV,    // Invalid memory reference
 		SIGSYS,     // Bad argument to routine (SVr4)
 		SIGTRAP,    // Trace/breakpoint trap
-		SIGUNUSED,  // Synonymous with SIGSYS
 		SIGXCPU,    // CPU time limit exceeded (4.2BSD)
 		SIGXFSZ,    // File size limit exceeded (4.2BSD)
 	};