diff --git a/extern/BSAOpt/hash.cpp b/extern/BSAOpt/hash.cpp
index 029c542799..08c807da45 100644
--- a/extern/BSAOpt/hash.cpp
+++ b/extern/BSAOpt/hash.cpp
@@ -31,6 +31,7 @@
 
 #include <cstdint>
 #include <algorithm>
+#include <cstring>
 
 #include "hash.hpp"