diff --git a/src/header/_aio/cbindgen.toml b/src/header/_aio/cbindgen.toml
index fd387cb50e..596c950abc 100644
--- a/src/header/_aio/cbindgen.toml
+++ b/src/header/_aio/cbindgen.toml
@@ -1,4 +1,8 @@
-sys_includes = []
+# signal brings in sigevent, size_t and timespec
+sys_includes = ["signal.h"]
+after_includes = """
+#include <bits/ssize-t.h> // for ssize_t from sys/types.h
+"""
 include_guard = "_RELIBC_AIO_H"
 language = "C"
 style = "Tag"
diff --git a/src/header/_aio/mod.rs b/src/header/_aio/mod.rs
index 2dbbc70938..1baafd0ef9 100644
--- a/src/header/_aio/mod.rs
+++ b/src/header/_aio/mod.rs
@@ -4,7 +4,7 @@
 
 use crate::{
     header::{signal::sigevent, time::timespec},
-    platform::types::{c_int, c_void},
+    platform::types::{c_int, c_void, size_t, ssize_t},
 };
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/aio.h.html>.
@@ -13,25 +13,25 @@ pub struct aiocb {
     pub aio_lio_opcode: c_int,
     pub aio_reqprio: c_int,
     pub aio_buf: *mut c_void,
-    pub aio_nbytes: usize,
+    pub aio_nbytes: size_t,
     pub aio_sigevent: sigevent,
 }
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/aio_read.html>.
 // #[unsafe(no_mangle)]
-pub extern "C" fn aio_read(aiocbp: *mut aiocb) -> c_int {
+pub unsafe extern "C" fn aio_read(aiocbp: *mut aiocb) -> c_int {
     unimplemented!();
 }
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/aio_write.html>.
 // #[unsafe(no_mangle)]
-pub extern "C" fn aio_write(aiocbp: *mut aiocb) -> c_int {
+pub unsafe extern "C" fn aio_write(aiocbp: *mut aiocb) -> c_int {
     unimplemented!();
 }
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/lio_listio.html>.
 // #[unsafe(no_mangle)]
-pub extern "C" fn lio_listio(
+pub unsafe extern "C" fn lio_listio(
     mode: c_int,
     list: *const *const aiocb,
     nent: c_int,
@@ -42,25 +42,25 @@ pub extern "C" fn lio_listio(
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/aio_error.html>.
 // #[unsafe(no_mangle)]
-pub extern "C" fn aio_error(aiocbp: *const aiocb) -> c_int {
+pub unsafe extern "C" fn aio_error(aiocbp: *const aiocb) -> c_int {
     unimplemented!();
 }
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/aio_return.html>.
 // #[unsafe(no_mangle)]
-pub extern "C" fn aio_return(aiocbp: *mut aiocb) -> usize {
+pub unsafe extern "C" fn aio_return(aiocbp: *mut aiocb) -> ssize_t {
     unimplemented!();
 }
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/aio_cancel.html>.
 // #[unsafe(no_mangle)]
-pub extern "C" fn aio_cancel(fildes: c_int, aiocbp: *mut aiocb) -> c_int {
+pub unsafe extern "C" fn aio_cancel(fildes: c_int, aiocbp: *mut aiocb) -> c_int {
     unimplemented!();
 }
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/aio_suspend.html>.
 // #[unsafe(no_mangle)]
-pub extern "C" fn aio_suspend(
+pub unsafe extern "C" fn aio_suspend(
     list: *const *const aiocb,
     nent: c_int,
     timeout: *const timespec,
@@ -70,6 +70,6 @@ pub extern "C" fn aio_suspend(
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/aio_fsync.html>.
 // #[unsafe(no_mangle)]
-pub extern "C" fn aio_fsync(operation: c_int, aiocbp: *mut aiocb) -> c_int {
+pub unsafe extern "C" fn aio_fsync(operation: c_int, aiocbp: *mut aiocb) -> c_int {
     unimplemented!();
 }
diff --git a/src/header/dl-tls/cbindgen.toml b/src/header/dl-tls/cbindgen.toml
index c09ca25349..6bffa9e5b7 100644
--- a/src/header/dl-tls/cbindgen.toml
+++ b/src/header/dl-tls/cbindgen.toml
@@ -1,5 +1,5 @@
 sys_includes = []
-include_guard = "_DL_TLS_H"
+include_guard = "_RELIBC_DL_TLS_H"
 language = "C"
 style = "Tag"
 no_includes = true
diff --git a/src/header/netinet_ip/cbindgen.toml b/src/header/netinet_ip/cbindgen.toml
index 11f2e66c4c..6dcb1636e7 100644
--- a/src/header/netinet_ip/cbindgen.toml
+++ b/src/header/netinet_ip/cbindgen.toml
@@ -1,5 +1,5 @@
 sys_includes = []
-include_guard = "_NETINET_IP_H"
+include_guard = "_RELIBC_NETINET_IP_H"
 language = "C"
 style = "Tag"
 no_includes = true