diff --git a/src/unix/mod.rs b/src/unix/mod.rs
index 8d06955bfc00..d083f7668800 100644
--- a/src/unix/mod.rs
+++ b/src/unix/mod.rs
@@ -178,7 +178,7 @@ s2! {
     }
 
     #[exhaustive] // FIXME(exhaustive): review for 1.0
-    #[cfg(not(target_os = "horizon"))]
+    #[cfg(not(any(target_os = "horizon", target_os = "nuttx")))]
     pub struct pollfd {
         pub fd: c_int,
         pub events: c_short,
diff --git a/src/unix/nuttx/mod.rs b/src/unix/nuttx/mod.rs
index 2380bba1ba40..8273e1739dfc 100644
--- a/src/unix/nuttx/mod.rs
+++ b/src/unix/nuttx/mod.rs
@@ -35,6 +35,7 @@ pub type suseconds_t = i32;
 pub type tcflag_t = u32;
 pub type clockid_t = c_int;
 pub type time_t = i64;
+pub type pollevent_t = u32;
 
 cfg_if! {
     if #[cfg(any(target_arch = "riscv32", target_arch = "riscv64"))] {
@@ -274,6 +275,17 @@ s! {
         pub imr_interface: in_addr,
         pub imr_sourceaddr: in_addr,
     }
+
+    pub struct pollfd {
+        pub fd: c_int,
+        pub events: pollevent_t,
+        pub revents: pollevent_t,
+
+        // Used internally by NuttX
+        pub arg: *const c_void,
+        pub cb: *const c_void,
+        pub r#priv: *const c_void,
+    }
 }
 
 // Reserved two pointer size for reserved area for some structures.
@@ -295,11 +307,11 @@ const __DEFAULT_RESERVED_SIZE__: usize = 2;
 
 const __SOCKADDR_STORAGE_SIZE__: usize = 36;
 const __PTHREAD_ATTR_SIZE__: usize = 5;
-const __PTHREAD_MUTEX_SIZE__: usize = 9;
-const __PTHREAD_COND_SIZE__: usize = 7;
+const __PTHREAD_MUTEX_SIZE__: usize = 13; // Assumes CONFIG_LIBC_MUTEX_BACKTRACE=0
+const __PTHREAD_COND_SIZE__: usize = 12;
 const __PTHREAD_CONDATTR_SIZE__: usize = 5;
-const __PTHREAD_RWLOCK_SIZE__: usize = 17;
-const __SEM_SIZE__: usize = 6;
+const __PTHREAD_RWLOCK_SIZE__: usize = 28;
+const __SEM_SIZE__: usize = 10;
 const __NAME_MAX__: usize = 64;
 const __FDSET_SIZE__: usize = 10;
 const __SIGSET_SIZE__: usize = 8;
@@ -518,17 +530,17 @@ pub const S_IWOTH: u32 = 0x002;
 pub const S_IXOTH: u32 = 0x001;
 
 // sys/poll.h
-pub const POLLIN: i16 = 0x01;
-pub const POLLRDNORM: i16 = 0x01;
-pub const POLLRDBAND: i16 = 0x01;
-pub const POLLPRI: i16 = 0x02;
-pub const POLLOUT: i16 = 0x04;
-pub const POLLWRNORM: i16 = 0x04;
-pub const POLLWRBAND: i16 = 0x04;
-pub const POLLHUP: i16 = 0x10;
-pub const POLLRDHUP: i16 = 0x10;
-pub const POLLERR: i16 = 0x08;
-pub const POLLNVAL: i16 = 0x20;
+pub const POLLIN: pollevent_t = 0x01;
+pub const POLLRDNORM: pollevent_t = 0x01;
+pub const POLLRDBAND: pollevent_t = 0x01;
+pub const POLLPRI: pollevent_t = 0x02;
+pub const POLLOUT: pollevent_t = 0x04;
+pub const POLLWRNORM: pollevent_t = 0x04;
+pub const POLLWRBAND: pollevent_t = 0x04;
+pub const POLLHUP: pollevent_t = 0x10;
+pub const POLLRDHUP: pollevent_t = 0x10;
+pub const POLLERR: pollevent_t = 0x08;
+pub const POLLNVAL: pollevent_t = 0x20;
 
 // sys/socket.h
 // Supported Protocol Families
@@ -696,4 +708,8 @@ extern "C" {
     pub fn eventfd(count: c_uint, flags: c_int) -> c_int;
     // unistd.h
     pub fn pipe2(fds: *mut c_int, flags: c_int) -> c_int;
+
+    pub fn sem_init(sem: *mut sem_t, pshared: c_int, value: c_uint) -> c_int;
+    pub fn sem_destroy(sem: *mut sem_t) -> c_int;
+    pub fn sem_getvalue(sem: *mut sem_t, sval: *mut c_int) -> c_int;
 }