$OpenBSD$

Index: runtime/druntime/src/core/stdc/string.d
--- runtime/druntime/src/core/stdc/string.d.orig
+++ runtime/druntime/src/core/stdc/string.d
@@ -80,6 +80,10 @@ else version (FreeBSD)
 {
     int strerror_r(int errnum, char* buf, size_t buflen);
 }
+else version (OpenBSD)
+{
+    int strerror_r(int errnum, scope char* buf, size_t buflen);
+}
 else version (Solaris)
 {
     int strerror_r(int errnum, char* buf, size_t buflen);
