$OpenBSD$

Index: runtime/druntime/src/core/sys/posix/sys/uio.d
--- runtime/druntime/src/core/sys/posix/sys/uio.d.orig
+++ runtime/druntime/src/core/sys/posix/sys/uio.d
@@ -70,6 +70,17 @@ else version( FreeBSD )
     ssize_t readv(int, in iovec*, int);
     ssize_t writev(int, in iovec*, int);
 }
+else version( OpenBSD )
+{
+    struct iovec
+    {
+        void*  iov_base;
+        size_t iov_len;
+    }
+
+    ssize_t readv(int, in iovec*, int);
+    ssize_t writev(int, in iovec*, int);
+}
 else version( DragonFlyBSD )
 {
     struct iovec
