diff --git a/src/unix/bsd/freebsdlike/mod.rs b/src/unix/bsd/freebsdlike/mod.rs
index d8e9ba41a60a3..44c9e004e6c2b 100644
--- a/src/unix/bsd/freebsdlike/mod.rs
+++ b/src/unix/bsd/freebsdlike/mod.rs
@@ -985,6 +985,14 @@ extern {
                   timeout: *const ::timespec) -> ::c_int;
     pub fn mincore(addr: *const ::c_void, len: ::size_t,
                    vec: *mut ::c_char) -> ::c_int;
+    pub fn pwritev(fd: ::c_int,
+                   iov: *const ::iovec,
+                   iovcnt: ::c_int,
+                   offset: ::off_t) -> ::ssize_t;
+    pub fn preadv(fd: ::c_int,
+                  iov: *const ::iovec,
+                  iovcnt: ::c_int,
+                  offset: ::off_t) -> ::ssize_t;
     pub fn sysctlnametomib(name: *const ::c_char,
                            mibp: *mut ::c_int,
                            sizep: *mut ::size_t)
diff --git a/src/unix/bsd/netbsdlike/mod.rs b/src/unix/bsd/netbsdlike/mod.rs
index e199cf24e5855..87756ff6fa295 100644
--- a/src/unix/bsd/netbsdlike/mod.rs
+++ b/src/unix/bsd/netbsdlike/mod.rs
@@ -580,6 +580,14 @@ extern {
     pub fn mkostemps(template: *mut ::c_char,
                      suffixlen: ::c_int,
                      flags: ::c_int) -> ::c_int;
+    pub fn pwritev(fd: ::c_int,
+                   iov: *const ::iovec,
+                   iovcnt: ::c_int,
+                   offset: ::off_t) -> ::ssize_t;
+    pub fn preadv(fd: ::c_int,
+                  iov: *const ::iovec,
+                  iovcnt: ::c_int,
+                  offset: ::off_t) -> ::ssize_t;
     pub fn futimens(fd: ::c_int, times: *const ::timespec) -> ::c_int;
     pub fn fdatasync(fd: ::c_int) -> ::c_int;
     pub fn openpty(amaster: *mut ::c_int,