diff --git a/libc-test/build.rs b/libc-test/build.rs
index 4716febb83f44..4095fca6f83f6 100644
--- a/libc-test/build.rs
+++ b/libc-test/build.rs
@@ -1278,6 +1278,7 @@ fn test_netbsd(target: &str) {
         "mqueue.h",
         "netinet/dccp.h",
         "sys/event.h",
+        (!netbsd9, "sys/eventfd.h"),
         "sys/quota.h",
         "sys/reboot.h",
         "sys/shm.h",
@@ -1323,6 +1324,7 @@ fn test_netbsd(target: &str) {
             "sighandler_t" => true,
             // Incomplete type in C
             "cpuset_t" => true,
+            "eventfd_t" if netbsd9 => true,
             _ => false,
         }
     });
@@ -1382,6 +1384,8 @@ fn test_netbsd(target: &str) {
             // FIXME(netbsd): Look into setting `_POSIX_C_SOURCE` to enable this
             "qsort_r" => true,
 
+            "eventfd" | "eventfd_read" | "eventfd_write" if netbsd9 => true,
+
             _ => false,
         }
     });
diff --git a/src/fuchsia/mod.rs b/src/fuchsia/mod.rs
index 1b99f98f021a2..49e1430f1cc4a 100644
--- a/src/fuchsia/mod.rs
+++ b/src/fuchsia/mod.rs
@@ -3918,7 +3918,7 @@ extern "C" {
         len: size_t,
         flags: c_uint,
     ) -> ssize_t;
-    pub fn eventfd(init: c_uint, flags: c_int) -> c_int;
+    pub fn eventfd(initval: c_uint, flags: c_int) -> c_int;
     pub fn sched_rr_get_interval(pid: crate::pid_t, tp: *mut crate::timespec) -> c_int;
     pub fn sem_timedwait(sem: *mut sem_t, abstime: *const crate::timespec) -> c_int;
     pub fn sem_getvalue(sem: *mut sem_t, sval: *mut c_int) -> c_int;
diff --git a/src/unix/bsd/freebsdlike/freebsd/mod.rs b/src/unix/bsd/freebsdlike/freebsd/mod.rs
index bc25a19e23cfb..6827ab069bf5d 100644
--- a/src/unix/bsd/freebsdlike/freebsd/mod.rs
+++ b/src/unix/bsd/freebsdlike/freebsd/mod.rs
@@ -4700,7 +4700,7 @@ extern "C" {
     pub fn memfd_create(name: *const c_char, flags: c_uint) -> c_int;
     pub fn setaudit(auditinfo: *const auditinfo_t) -> c_int;
 
-    pub fn eventfd(init: c_uint, flags: c_int) -> c_int;
+    pub fn eventfd(initval: c_uint, flags: c_int) -> c_int;
     pub fn eventfd_read(fd: c_int, value: *mut eventfd_t) -> c_int;
     pub fn eventfd_write(fd: c_int, value: eventfd_t) -> c_int;
 
diff --git a/src/unix/bsd/netbsdlike/netbsd/mod.rs b/src/unix/bsd/netbsdlike/netbsd/mod.rs
index 2c30a585b7fd6..c8fb9c582a57e 100644
--- a/src/unix/bsd/netbsdlike/netbsd/mod.rs
+++ b/src/unix/bsd/netbsdlike/netbsd/mod.rs
@@ -7,6 +7,7 @@ use crate::{
 };
 
 pub type blksize_t = i32;
+pub type eventfd_t = u64;
 pub type fsblkcnt_t = u64;
 pub type fsfilcnt_t = u64;
 pub type idtype_t = c_int;
@@ -1742,6 +1743,11 @@ pub const RTA_TAG: c_int = 0x100;
 pub const RTAX_TAG: c_int = 8;
 pub const RTAX_MAX: c_int = 9;
 
+// For eventfd
+pub const EFD_SEMAPHORE: c_int = crate::O_RDWR;
+pub const EFD_NONBLOCK: c_int = crate::O_NONBLOCK;
+pub const EFD_CLOEXEC: c_int = crate::O_CLOEXEC;
+
 // sys/timerfd.h
 pub const TFD_CLOEXEC: i32 = crate::O_CLOEXEC;
 pub const TFD_NONBLOCK: i32 = crate::O_NONBLOCK;
@@ -2197,6 +2203,10 @@ extern "C" {
     pub fn getmntinfo(mntbufp: *mut *mut crate::statvfs, flags: c_int) -> c_int;
     pub fn getvfsstat(buf: *mut crate::statvfs, bufsize: size_t, flags: c_int) -> c_int;
 
+    pub fn eventfd(val: c_uint, flags: c_int) -> c_int;
+    pub fn eventfd_read(efd: c_int, valp: *mut eventfd_t) -> c_int;
+    pub fn eventfd_write(efd: c_int, val: eventfd_t) -> c_int;
+
     // Added in `NetBSD` 10.0
     pub fn timerfd_create(clockid: crate::clockid_t, flags: c_int) -> c_int;
     pub fn timerfd_gettime(fd: c_int, curr_value: *mut crate::itimerspec) -> c_int;
diff --git a/src/unix/linux_like/android/mod.rs b/src/unix/linux_like/android/mod.rs
index 5625704682e3d..4fb647235c982 100644
--- a/src/unix/linux_like/android/mod.rs
+++ b/src/unix/linux_like/android/mod.rs
@@ -3521,7 +3521,7 @@ extern "C" {
         len: size_t,
         flags: c_uint,
     ) -> ssize_t;
-    pub fn eventfd(init: c_uint, flags: c_int) -> c_int;
+    pub fn eventfd(initval: c_uint, flags: c_int) -> c_int;
     pub fn eventfd_read(fd: c_int, value: *mut eventfd_t) -> c_int;
     pub fn eventfd_write(fd: c_int, value: eventfd_t) -> c_int;
     pub fn sched_rr_get_interval(pid: crate::pid_t, tp: *mut crate::timespec) -> c_int;
diff --git a/src/unix/linux_like/linux/mod.rs b/src/unix/linux_like/linux/mod.rs
index d0ea99e28b034..652c780d103fd 100644
--- a/src/unix/linux_like/linux/mod.rs
+++ b/src/unix/linux_like/linux/mod.rs
@@ -6057,7 +6057,7 @@ extern "C" {
         len: size_t,
         flags: c_uint,
     ) -> ssize_t;
-    pub fn eventfd(init: c_uint, flags: c_int) -> c_int;
+    pub fn eventfd(initval: c_uint, flags: c_int) -> c_int;
     pub fn eventfd_read(fd: c_int, value: *mut eventfd_t) -> c_int;
     pub fn eventfd_write(fd: c_int, value: eventfd_t) -> c_int;
 
diff --git a/src/unix/solarish/illumos.rs b/src/unix/solarish/illumos.rs
index d83a24075e0b4..c0a17823bb9a7 100644
--- a/src/unix/solarish/illumos.rs
+++ b/src/unix/solarish/illumos.rs
@@ -212,7 +212,7 @@ pub const TFD_TIMER_ABSTIME: i32 = 1 << 0;
 pub const TFD_TIMER_CANCEL_ON_SET: i32 = 1 << 1;
 
 extern "C" {
-    pub fn eventfd(init: c_uint, flags: c_int) -> c_int;
+    pub fn eventfd(initval: c_uint, flags: c_int) -> c_int;
 
     pub fn epoll_pwait(
         epfd: c_int,