diff --git a/Cargo.toml b/Cargo.toml
index 2ed76957e1..dcf6c01ec1 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -33,11 +33,12 @@ dangling_pointers_from_temporaries = "deny"
 irrefutable_let_patterns = "deny"
 mismatched_lifetime_syntaxes = "deny"
 non_camel_case_types = "allow"
-non_snake_case = "allow"
-non_upper_case_globals = "allow"
+non_snake_case = "allow" # TODO review occuurences
+non_upper_case_globals = "allow" # TODO review occuurences
 unpredictable_function_pointer_comparisons = "deny"
 unsafe_op_in_unsafe_fn = "deny"
 unused_imports = "deny"
+unused_must_use = "deny"
 unused_mut = "deny"
 unused_unsafe = "deny"
 unused_variables = "allow" # TODO review occurrences (too many for now)
diff --git a/src/header/glob/mod.rs b/src/header/glob/mod.rs
index e71561a9d0..72e5010d5f 100644
--- a/src/header/glob/mod.rs
+++ b/src/header/glob/mod.rs
@@ -164,7 +164,7 @@ pub unsafe extern "C" fn globfree(pglob: *mut glob_t) {
             }
             if !path.is_null() {
                 unsafe {
-                    CString::from_raw(path);
+                    drop(CString::from_raw(path));
                 }
             }
         }
diff --git a/src/header/netdb/dns/mod.rs b/src/header/netdb/dns/mod.rs
index 2d73281b61..9d7e44bd1c 100644
--- a/src/header/netdb/dns/mod.rs
+++ b/src/header/netdb/dns/mod.rs
@@ -132,8 +132,8 @@ impl Dns {
         let flags = pop_n16!();
         let queries_len = pop_n16!();
         let answers_len = pop_n16!();
-        pop_n16!();
-        pop_n16!();
+        let _ = pop_n16!();
+        let _ = pop_n16!();
 
         let mut queries = Vec::new();
         for _query_i in 0..queries_len {
diff --git a/src/header/netdb/host.rs b/src/header/netdb/host.rs
index 59ad6190a1..73e3604592 100644
--- a/src/header/netdb/host.rs
+++ b/src/header/netdb/host.rs
@@ -37,7 +37,7 @@ pub static mut HOST_STAYOPEN: c_int = 0;
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn endhostent() {
     if unsafe { HOSTDB } >= 0 {
-        Sys::close(unsafe { HOSTDB });
+        if let Ok(()) = Sys::close(unsafe { HOSTDB }) {}; // TODO handle error
     }
     unsafe { HOSTDB = -1 };
 }
@@ -48,7 +48,7 @@ pub unsafe extern "C" fn sethostent(stayopen: c_int) {
     if unsafe { HOSTDB } < 0 {
         unsafe { HOSTDB = Sys::open(c"/etc/hosts".into(), O_RDONLY, 0).or_minus_one_errno() }
     } else {
-        Sys::lseek(unsafe { HOSTDB }, 0, SEEK_SET);
+        if let Ok(_) = Sys::lseek(unsafe { HOSTDB }, 0, SEEK_SET) {}; // TODO handle error
     }
     unsafe { H_POS = 0 };
 }
diff --git a/src/header/netdb/lookup.rs b/src/header/netdb/lookup.rs
index c5da3fd320..7c8e405aaa 100644
--- a/src/header/netdb/lookup.rs
+++ b/src/header/netdb/lookup.rs
@@ -39,10 +39,10 @@ pub fn lookup_host(host: &str) -> Result<LookupHost, c_int> {
 
     if let Some(dns_addr) = parse_ipv4_string(&dns_string) {
         let mut timespec = timespec::default();
-        Sys::clock_gettime(
+        if let Ok(()) = Sys::clock_gettime(
             time::constants::CLOCK_REALTIME,
             Out::from_mut(&mut timespec),
-        );
+        ) {}; // TODO handle error
         let tid = (timespec.tv_nsec >> 16) as u16;
 
         let packet = Dns {
@@ -76,14 +76,14 @@ pub fn lookup_host(host: &str) -> Result<LookupHost, c_int> {
                 return Err(EIO);
             }
             if sys_socket::send(sock, packet_data_ptr, packet_data_len, 0) < 0 {
-                Box::from_raw(packet_data_ptr);
+                drop(Box::from_raw(packet_data_ptr));
                 return Err(EIO);
             }
             sock
         };
 
         unsafe {
-            Box::from_raw(packet_data_ptr);
+            drop(Box::from_raw(packet_data_ptr));
         }
 
         let i = 0 as socklen_t;
@@ -141,10 +141,10 @@ pub fn lookup_addr(addr: in_addr) -> Result<Vec<Vec<u8>>, c_int> {
         );
 
         let mut timespec = timespec::default();
-        Sys::clock_gettime(
+        if let Ok(()) = Sys::clock_gettime(
             time::constants::CLOCK_REALTIME,
             Out::from_mut(&mut timespec),
-        );
+        ) {}; // TODO handle error
         let tid = (timespec.tv_nsec >> 16) as u16;
 
         let packet = Dns {
@@ -187,7 +187,7 @@ pub fn lookup_addr(addr: in_addr) -> Result<Vec<Vec<u8>>, c_int> {
         }
 
         unsafe {
-            Box::from_raw(packet_data_ptr);
+            drop(Box::from_raw(packet_data_ptr));
         }
 
         let i = mem::size_of::<sockaddr_in>() as socklen_t;
diff --git a/src/header/netdb/mod.rs b/src/header/netdb/mod.rs
index 8629270e42..42635c4e5d 100644
--- a/src/header/netdb/mod.rs
+++ b/src/header/netdb/mod.rs
@@ -181,21 +181,21 @@ fn bytes_to_box_str(bytes: &[u8]) -> Box<str> {
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/endnetent.html>.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn endnetent() {
-    Sys::close(unsafe { NETDB });
+    if let Ok(()) = Sys::close(unsafe { NETDB }) {}; // TODO handle error
     unsafe { NETDB = 0 };
 }
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/endprotoent.html>.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn endprotoent() {
-    Sys::close(unsafe { PROTODB });
+    if let Ok(()) = Sys::close(unsafe { PROTODB }) {}; // TODO handle error
     unsafe { PROTODB = 0 };
 }
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/endservent.html>.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn endservent() {
-    Sys::close(unsafe { SERVDB });
+    if let Ok(()) = Sys::close(unsafe { SERVDB }) {}; // TODO handle error
     unsafe { SERVDB = 0 };
 }
 
@@ -783,7 +783,7 @@ pub unsafe extern "C" fn setnetent(stayopen: c_int) {
     if unsafe { NETDB } == 0 {
         unsafe { NETDB = Sys::open(c"/etc/networks".into(), O_RDONLY, 0).or_minus_one_errno() }
     } else {
-        Sys::lseek(unsafe { NETDB }, 0, SEEK_SET);
+        if let Ok(_) = Sys::lseek(unsafe { NETDB }, 0, SEEK_SET) {}; // TODO handle errror
         unsafe { N_POS = 0 };
     }
 }
@@ -795,7 +795,7 @@ pub unsafe extern "C" fn setprotoent(stayopen: c_int) {
     if unsafe { PROTODB } == 0 {
         unsafe { PROTODB = Sys::open(c"/etc/protocols".into(), O_RDONLY, 0).or_minus_one_errno() }
     } else {
-        Sys::lseek(unsafe { PROTODB }, 0, SEEK_SET);
+        if let Ok(_) = Sys::lseek(unsafe { PROTODB }, 0, SEEK_SET) {}; // TODO handle error
         unsafe { P_POS = 0 };
     }
 }
@@ -807,7 +807,7 @@ pub unsafe extern "C" fn setservent(stayopen: c_int) {
     if unsafe { SERVDB } == 0 {
         unsafe { SERVDB = Sys::open(c"/etc/services".into(), O_RDONLY, 0).or_minus_one_errno() }
     } else {
-        Sys::lseek(unsafe { SERVDB }, 0, SEEK_SET);
+        if let Ok(_) = Sys::lseek(unsafe { SERVDB }, 0, SEEK_SET) {}; // TODO handle error
         unsafe { S_POS = 0 };
     }
 }
@@ -1030,9 +1030,9 @@ pub unsafe extern "C" fn freeaddrinfo(res: *mut addrinfo) {
         }
         if !bai.ai_addr.is_null() {
             if bai.ai_addrlen == mem::size_of::<sockaddr_in>() as socklen_t {
-                unsafe { Box::from_raw(bai.ai_addr as *mut sockaddr_in) };
+                unsafe { drop(Box::from_raw(bai.ai_addr as *mut sockaddr_in)) };
             } else if bai.ai_addrlen == mem::size_of::<sockaddr_in6>() as socklen_t {
-                unsafe { Box::from_raw(bai.ai_addr as *mut sockaddr_in6) };
+                unsafe { drop(Box::from_raw(bai.ai_addr as *mut sockaddr_in6)) };
             } else {
                 todo_skip!(0, "freeaddrinfo: unknown ai_addrlen {}", bai.ai_addrlen);
             }
diff --git a/src/header/pty/linux.rs b/src/header/pty/linux.rs
index 5c580d612d..2ee23cc9e6 100644
--- a/src/header/pty/linux.rs
+++ b/src/header/pty/linux.rs
@@ -38,7 +38,7 @@ pub(super) unsafe fn openpty(name: &mut [u8]) -> Result<(c_int, c_int), ()> {
     }
 
     let mut cursor = Cursor::new(name);
-    write!(cursor, "/dev/pts/{}\0", ptn);
+    if let Ok(()) = write!(cursor, "/dev/pts/{}\0", ptn) {}; // TODO handle error
 
     let slave = unsafe {
         fcntl::open(
diff --git a/src/header/regex/mod.rs b/src/header/regex/mod.rs
index 5978dddc24..50d645fc60 100644
--- a/src/header/regex/mod.rs
+++ b/src/header/regex/mod.rs
@@ -90,7 +90,7 @@ pub unsafe extern "C" fn regcomp(out: *mut regex_t, pat: *const c_char, cflags:
 #[unsafe(no_mangle)]
 #[linkage = "weak"] // redefined in GIT
 pub unsafe extern "C" fn regfree(regex: *mut regex_t) {
-    unsafe { Box::from_raw((*regex).ptr) };
+    unsafe { drop(Box::from_raw((*regex).ptr)) };
 }
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/regexec.html>.
diff --git a/src/header/semaphore/mod.rs b/src/header/semaphore/mod.rs
index 0dcf2144b1..59d94f84ca 100644
--- a/src/header/semaphore/mod.rs
+++ b/src/header/semaphore/mod.rs
@@ -81,7 +81,7 @@ pub unsafe extern "C" fn sem_unlink(name: *const c_char) -> c_int {
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/sem_trywait.html>.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn sem_wait(sem: *mut sem_t) -> c_int {
-    unsafe { get(sem) }.wait(None, CLOCK_MONOTONIC);
+    if let Ok(()) = unsafe { get(sem) }.wait(None, CLOCK_MONOTONIC) {}; // TODO handle error
 
     0
 }
@@ -93,7 +93,7 @@ pub unsafe extern "C" fn sem_clockwait(
     clock_id: clockid_t,
     abstime: *const timespec,
 ) -> c_int {
-    unsafe { get(sem) }.wait(Some(&unsafe { *abstime }), clock_id);
+    if let Ok(()) = unsafe { get(sem) }.wait(Some(&unsafe { *abstime }), clock_id) {}; // TODO handle error
 
     0
 }
@@ -101,7 +101,7 @@ pub unsafe extern "C" fn sem_clockwait(
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/sem_timedwait.html>.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn sem_timedwait(sem: *mut sem_t, abstime: *const timespec) -> c_int {
-    unsafe { get(sem) }.wait(Some(&unsafe { *abstime }), CLOCK_REALTIME);
+    if let Ok(()) = unsafe { get(sem) }.wait(Some(&unsafe { *abstime }), CLOCK_REALTIME) {}; // TODO handle error
 
     0
 }
diff --git a/src/header/stdio/mod.rs b/src/header/stdio/mod.rs
index 45c128b9b9..fa9bb72aa0 100644
--- a/src/header/stdio/mod.rs
+++ b/src/header/stdio/mod.rs
@@ -580,7 +580,7 @@ pub unsafe extern "C" fn fopen(filename: *const c_char, mode: *const c_char) ->
         .map(|f| Box::into_raw(f))
         .map_err(|err| {
             // TODO: guard type
-            Sys::close(fd);
+            if let Ok(()) = Sys::close(fd) {}; // TODO handle error
             err
         })
         .or_errno_null_mut()
@@ -1320,11 +1320,11 @@ pub unsafe extern "C" fn tmpfile() -> *mut FILE {
     let fp = unsafe { fdopen(fd, c"w+".as_ptr()) };
     {
         let file_name = unsafe { CStr::from_ptr(file_name) };
-        Sys::unlink(file_name);
+        if let Ok(()) = Sys::unlink(file_name) {}; // TODO handle error
     }
 
     if fp.is_null() {
-        Sys::close(fd);
+        if let Ok(()) = Sys::close(fd) {}; // TODO handle error
     }
 
     fp
diff --git a/src/header/stdio/printf.rs b/src/header/stdio/printf.rs
index 33c8414dff..22d8cb8f8e 100644
--- a/src/header/stdio/printf.rs
+++ b/src/header/stdio/printf.rs
@@ -697,7 +697,7 @@ pub(crate) unsafe fn inner_printf<T: c_str::Kind>(
                 } else {
                     // TODO: wcsrtombs wrapper
                     for c in text.iter().filter_map(|u| char::from_u32((*u).into())) {
-                        write!(w, "{}", c);
+                        if let Ok(()) = write!(w, "{}", c) {}; // TODO handle error
                     }
                 }
                 continue;
diff --git a/src/header/sys_stat/mod.rs b/src/header/sys_stat/mod.rs
index bbccc3613b..c9f559726d 100644
--- a/src/header/sys_stat/mod.rs
+++ b/src/header/sys_stat/mod.rs
@@ -157,7 +157,7 @@ pub unsafe extern "C" fn lstat(path: *const c_char, buf: *mut stat) -> c_int {
     // TODO: Rustify
     let res = Sys::fstat(fd, buf).map(|()| 0).or_minus_one_errno();
 
-    Sys::close(fd);
+    if let Ok(()) = Sys::close(fd) {}; // TODO handle error
 
     res
 }
@@ -230,7 +230,7 @@ pub unsafe extern "C" fn stat(file: *const c_char, buf: *mut stat) -> c_int {
     // TODO: Rustify
     let res = Sys::fstat(fd, buf).map(|()| 0).or_minus_one_errno();
 
-    Sys::close(fd);
+    if let Ok(()) = Sys::close(fd) {}; // TODO handle error
 
     res
 }
diff --git a/src/header/sys_statvfs/mod.rs b/src/header/sys_statvfs/mod.rs
index a48d924311..866768b885 100644
--- a/src/header/sys_statvfs/mod.rs
+++ b/src/header/sys_statvfs/mod.rs
@@ -52,7 +52,7 @@ pub unsafe extern "C" fn statvfs(file: *const c_char, buf: *mut statvfs) -> c_in
 
     let res = Sys::fstatvfs(fd, buf).map(|()| 0).or_minus_one_errno();
 
-    Sys::close(fd);
+    if let Ok(()) = Sys::close(fd) {}; // TODO handle error
 
     res
 }
diff --git a/src/header/sys_syslog/mod.rs b/src/header/sys_syslog/mod.rs
index 976151e001..f2277cd740 100644
--- a/src/header/sys_syslog/mod.rs
+++ b/src/header/sys_syslog/mod.rs
@@ -111,7 +111,7 @@ pub unsafe extern "C" fn openlog(ident: *const c_char, opt: c_int, facility: c_i
 
     // Ensure log is ready to write now instead of checking on the first message.
     if conf.contains(logger::Config::NoDelay) {
-        params.open_logger();
+        if let Ok(()) = params.open_logger() {}; // TODO handle error
     }
 }
 
diff --git a/src/header/unistd/mod.rs b/src/header/unistd/mod.rs
index 6facf6a046..e7114e2d59 100644
--- a/src/header/unistd/mod.rs
+++ b/src/header/unistd/mod.rs
@@ -1060,7 +1060,7 @@ pub unsafe extern "C" fn symlink(path1: *const c_char, path2: *const c_char) ->
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/sync.html>.
 #[unsafe(no_mangle)]
 pub extern "C" fn sync() {
-    Sys::sync();
+    if let Ok(()) = Sys::sync() {}; // TODO handle error
 }
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/tcgetpgrp.html>.
@@ -1094,7 +1094,7 @@ pub unsafe extern "C" fn truncate(path: *const c_char, length: off_t) -> c_int {
 
     let res = ftruncate(fd, length);
 
-    Sys::close(fd);
+    if let Ok(()) = Sys::close(fd) {}; // TODO handle error
 
     res
 }
diff --git a/src/header/unistd/sysconf/redox.rs b/src/header/unistd/sysconf/redox.rs
index 651b43adbf..140427edb1 100644
--- a/src/header/unistd/sysconf/redox.rs
+++ b/src/header/unistd/sysconf/redox.rs
@@ -97,7 +97,7 @@ pub fn get_mem_stat() -> Result<sys_statvfs::statvfs, Errno> {
     let fd = Sys::open(c"/scheme/memory".into(), fcntl::O_PATH, 0)?;
     let mut buf = sys_statvfs::statvfs::default();
     let res = Sys::fstatvfs(fd, Out::from_mut(&mut buf));
-    Sys::close(fd);
+    if let Ok(()) = Sys::close(fd) {}; // TODO handle error
     let _ = res?;
     return Ok(buf);
 }
diff --git a/src/platform/mod.rs b/src/platform/mod.rs
index 48faaf4000..d8df40e86a 100644
--- a/src/platform/mod.rs
+++ b/src/platform/mod.rs
@@ -108,14 +108,14 @@ impl FileWriter {
 
 impl fmt::Write for FileWriter {
     fn write_str(&mut self, s: &str) -> fmt::Result {
-        self.write(s.as_bytes());
+        if let Ok(()) = self.write(s.as_bytes()) {}; // TODO handle error
         Ok(())
     }
 }
 
 impl WriteByte for FileWriter {
     fn write_u8(&mut self, byte: u8) -> fmt::Result {
-        self.write(&[byte]);
+        if let Ok(()) = self.write(&[byte]) {}; // TODO handle error
         Ok(())
     }
 }
diff --git a/src/platform/redox/ptrace.rs b/src/platform/redox/ptrace.rs
index a8668be624..d9a110e021 100644
--- a/src/platform/redox/ptrace.rs
+++ b/src/platform/redox/ptrace.rs
@@ -167,7 +167,7 @@ unsafe fn inner_ptrace(
         | sys_ptrace::PTRACE_SYSCALL
         | sys_ptrace::PTRACE_SYSEMU
         | sys_ptrace::PTRACE_SYSEMU_SINGLESTEP => {
-            Sys::kill(pid, signal::SIGCONT as _);
+            if let Ok(()) = Sys::kill(pid, signal::SIGCONT as _) {}; // TODO handle error
 
             // TODO: Translate errors
             let syscall = syscall::PTRACE_STOP_PRE_SYSCALL | syscall::PTRACE_STOP_POST_SYSCALL;
diff --git a/src/sync/barrier.rs b/src/sync/barrier.rs
index 9ae84a60ef..6204a235ef 100644
--- a/src/sync/barrier.rs
+++ b/src/sync/barrier.rs
@@ -40,7 +40,7 @@ impl Barrier {
         if guard.count == self.original_count.get() {
             guard.gen_id = guard.gen_id.wrapping_add(1);
             guard.count = 0;
-            self.cvar.broadcast();
+            if let Ok(()) = self.cvar.broadcast() {}; // TODO handle error
 
             drop(guard);
 
diff --git a/src/sync/mod.rs b/src/sync/mod.rs
index 4a1ffc8498..cd818df549 100644
--- a/src/sync/mod.rs
+++ b/src/sync/mod.rs
@@ -137,11 +137,10 @@ pub fn rttime() -> timespec {
     unsafe {
         let mut time = MaybeUninit::uninit();
 
-        // TODO: Handle error
-        Sys::clock_gettime(
+        if let Ok(()) = Sys::clock_gettime(
             crate::header::time::CLOCK_REALTIME,
             Out::from_uninit_mut(&mut time),
-        );
+        ) {}; // TODO handle error
 
         time.assume_init()
     }