diff --git a/lib/std/c.zig b/lib/std/c.zig
index 7a1f47e6ac57..9b29d9a2c475 100644
--- a/lib/std/c.zig
+++ b/lib/std/c.zig
@@ -73,10 +73,10 @@ pub fn versionCheck(glibc_version: builtin.Version) type {
 
 pub extern "c" var environ: [*:null]?[*:0]u8;
 
-pub extern "c" fn fopen(filename: [*:0]const u8, modes: [*:0]const u8) ?*FILE;
+pub extern "c" fn fopen(noalias filename: [*:0]const u8, noalias modes: [*:0]const u8) ?*FILE;
 pub extern "c" fn fclose(stream: *FILE) c_int;
-pub extern "c" fn fwrite(ptr: [*]const u8, size_of_type: usize, item_count: usize, stream: *FILE) usize;
-pub extern "c" fn fread(ptr: [*]u8, size_of_type: usize, item_count: usize, stream: *FILE) usize;
+pub extern "c" fn fwrite(noalias ptr: [*]const u8, size_of_type: usize, item_count: usize, noalias stream: *FILE) usize;
+pub extern "c" fn fread(noalias ptr: [*]u8, size_of_type: usize, item_count: usize, noalias stream: *FILE) usize;
 
 pub extern "c" fn printf(format: [*:0]const u8, ...) c_int;
 pub extern "c" fn abort() noreturn;
@@ -153,9 +153,9 @@ pub extern "c" fn socketpair(domain: c_uint, sock_type: c_uint, protocol: c_uint
 pub extern "c" fn listen(sockfd: fd_t, backlog: c_uint) c_int;
 pub extern "c" fn getsockname(sockfd: fd_t, noalias addr: *sockaddr, noalias addrlen: *socklen_t) c_int;
 pub extern "c" fn connect(sockfd: fd_t, sock_addr: *const sockaddr, addrlen: socklen_t) c_int;
-pub extern "c" fn accept(sockfd: fd_t, addr: ?*sockaddr, addrlen: ?*socklen_t) c_int;
-pub extern "c" fn accept4(sockfd: fd_t, addr: ?*sockaddr, addrlen: ?*socklen_t, flags: c_uint) c_int;
-pub extern "c" fn getsockopt(sockfd: fd_t, level: u32, optname: u32, optval: ?*c_void, optlen: *socklen_t) c_int;
+pub extern "c" fn accept(sockfd: fd_t, noalias addr: ?*sockaddr, noalias addrlen: ?*socklen_t) c_int;
+pub extern "c" fn accept4(sockfd: fd_t, noalias addr: ?*sockaddr, noalias addrlen: ?*socklen_t, flags: c_uint) c_int;
+pub extern "c" fn getsockopt(sockfd: fd_t, level: u32, optname: u32, noalias optval: ?*c_void, noalias optlen: *socklen_t) c_int;
 pub extern "c" fn setsockopt(sockfd: fd_t, level: u32, optname: u32, optval: ?*const c_void, optlen: socklen_t) c_int;
 pub extern "c" fn send(sockfd: fd_t, buf: *const c_void, len: usize, flags: u32) isize;
 pub extern "c" fn sendto(