diff --git a/lib/std/event/loop.zig b/lib/std/event/loop.zig
index f0ac85d4f0..fc122a1862 100644
--- a/lib/std/event/loop.zig
+++ b/lib/std/event/loop.zig
@@ -502,18 +502,43 @@ pub const Loop = struct {
     }
 
     pub fn waitUntilFdReadable(self: *Loop, fd: os.fd_t) void {
-        return self.linuxWaitFd(fd, os.EPOLLET | os.EPOLLONESHOT | os.EPOLLIN);
+        switch (builtin.os.tag) {
+            .linux => {
+                self.linuxWaitFd(fd, os.EPOLLET | os.EPOLLONESHOT | os.EPOLLIN);
+            },
+            .macosx, .freebsd, .netbsd, .dragonfly => {
+                self.bsdWaitKev(@intCast(usize, fd), os.EVFILT_READ, os.EV_ONESHOT);
+            },
+            else => @compileError("Unsupported OS"),
+        }
     }
 
     pub fn waitUntilFdWritable(self: *Loop, fd: os.fd_t) void {
-        return self.linuxWaitFd(fd, os.EPOLLET | os.EPOLLONESHOT | os.EPOLLOUT);
+        switch (builtin.os.tag) {
+            .linux => {
+                self.linuxWaitFd(fd, os.EPOLLET | os.EPOLLONESHOT | os.EPOLLOUT);
+            },
+            .macosx, .freebsd, .netbsd, .dragonfly => {
+                self.bsdWaitKev(@intCast(usize, fd), os.EVFILT_WRITE, os.EV_ONESHOT);
+            },
+            else => @compileError("Unsupported OS"),
+        }
     }
 
     pub fn waitUntilFdWritableOrReadable(self: *Loop, fd: os.fd_t) void {
-        return self.linuxWaitFd(fd, os.EPOLLET | os.EPOLLONESHOT | os.EPOLLOUT | os.EPOLLIN);
+        switch (builtin.os.tag) {
+            .linux => {
+                self.linuxWaitFd(@intCast(usize, fd), os.EPOLLET | os.EPOLLONESHOT | os.EPOLLOUT | os.EPOLLIN);
+            },
+            .macosx, .freebsd, .netbsd, .dragonfly => {
+                self.bsdWaitKev(@intCast(usize, fd), os.EVFILT_READ, os.EV_ONESHOT);
+                self.bsdWaitKev(@intCast(usize, fd), os.EVFILT_WRITE, os.EV_ONESHOT);
+            },
+            else => @compileError("Unsupported OS"),
+        }
     }
 
-    pub async fn bsdWaitKev(self: *Loop, ident: usize, filter: i16, fflags: u32) !os.Kevent {
+    pub async fn bsdWaitKev(self: *Loop, ident: usize, filter: i16, fflags: u32) void {
         var resume_node = ResumeNode.Basic{
             .base = ResumeNode{
                 .id = ResumeNode.Id.Basic,
@@ -524,40 +549,37 @@ pub const Loop = struct {
         };
         defer self.bsdRemoveKev(ident, filter);
         suspend {
-            try self.bsdAddKev(&resume_node, ident, filter, fflags);
+            self.bsdAddKev(&resume_node, ident, filter, fflags) catch unreachable;
         }
-        return resume_node.kev;
     }
 
     /// resume_node must live longer than the anyframe that it holds a reference to.
     pub fn bsdAddKev(self: *Loop, resume_node: *ResumeNode.Basic, ident: usize, filter: i16, fflags: u32) !void {
         self.beginOneEvent();
         errdefer self.finishOneEvent();
-        var kev = os.Kevent{
+        var kev = [1]os.Kevent{os.Kevent{
             .ident = ident,
             .filter = filter,
             .flags = os.EV_ADD | os.EV_ENABLE | os.EV_CLEAR,
             .fflags = fflags,
             .data = 0,
             .udata = @ptrToInt(&resume_node.base),
-        };
-        const kevent_array = (*const [1]os.Kevent)(&kev);
-        const empty_kevs = ([*]os.Kevent)(undefined)[0..0];
-        _ = try os.kevent(self.os_data.kqfd, kevent_array, empty_kevs, null);
+        }};
+        const empty_kevs = &[0]os.Kevent{};
+        _ = try os.kevent(self.os_data.kqfd, &kev, empty_kevs, null);
     }
 
     pub fn bsdRemoveKev(self: *Loop, ident: usize, filter: i16) void {
-        var kev = os.Kevent{
+        var kev = [1]os.Kevent{os.Kevent{
             .ident = ident,
             .filter = filter,
             .flags = os.EV_DELETE,
             .fflags = 0,
             .data = 0,
             .udata = 0,
-        };
-        const kevent_array = (*const [1]os.Kevent)(&kev);
-        const empty_kevs = ([*]os.Kevent)(undefined)[0..0];
-        _ = os.kevent(self.os_data.kqfd, kevent_array, empty_kevs, null) catch undefined;
+        }};
+        const empty_kevs = &[0]os.Kevent{};
+        _ = os.kevent(self.os_data.kqfd, &kev, empty_kevs, null) catch undefined;
         self.finishOneEvent();
     }
 
@@ -712,7 +734,7 @@ pub const Loop = struct {
     }
 
     /// Performs an async `os.open` using a separate thread.
-    pub fn openZ(self: *Loop, file_path: [*:0]const u8, flags: u32, mode: usize) os.OpenError!os.fd_t {
+    pub fn openZ(self: *Loop, file_path: [*:0]const u8, flags: u32, mode: os.mode_t) os.OpenError!os.fd_t {
         var req_node = Request.Node{
             .data = .{
                 .msg = .{
@@ -733,7 +755,7 @@ pub const Loop = struct {
     }
 
     /// Performs an async `os.opent` using a separate thread.
-    pub fn openatZ(self: *Loop, fd: os.fd_t, file_path: [*:0]const u8, flags: u32, mode: usize) os.OpenError!os.fd_t {
+    pub fn openatZ(self: *Loop, fd: os.fd_t, file_path: [*:0]const u8, flags: u32, mode: os.mode_t) os.OpenError!os.fd_t {
         var req_node = Request.Node{
             .data = .{
                 .msg = .{
diff --git a/lib/std/os.zig b/lib/std/os.zig
index 9502e8d9df..5a502035d5 100644
--- a/lib/std/os.zig
+++ b/lib/std/os.zig
@@ -374,7 +374,7 @@ pub fn readv(fd: fd_t, iov: []const iovec) ReadError!usize {
         const first = iov[0];
         return read(fd, first.iov_base[0..first.iov_len]);
     }
-    
+
     const iov_count = math.cast(u31, iov.len) catch math.maxInt(u31);
     while (true) {
         // TODO handle the case when iov_len is too large and get rid of this @intCast
@@ -859,7 +859,7 @@ pub const OpenError = error{
 /// Open and possibly create a file. Keeps trying if it gets interrupted.
 /// See also `openC`.
 /// TODO support windows
-pub fn open(file_path: []const u8, flags: u32, perm: usize) OpenError!fd_t {
+pub fn open(file_path: []const u8, flags: u32, perm: mode_t) OpenError!fd_t {
     const file_path_c = try toPosixPath(file_path);
     return openZ(&file_path_c, flags, perm);
 }
@@ -869,7 +869,7 @@ pub const openC = @compileError("deprecated: renamed to openZ");
 /// Open and possibly create a file. Keeps trying if it gets interrupted.
 /// See also `open`.
 /// TODO support windows
-pub fn openZ(file_path: [*:0]const u8, flags: u32, perm: usize) OpenError!fd_t {
+pub fn openZ(file_path: [*:0]const u8, flags: u32, perm: mode_t) OpenError!fd_t {
     while (true) {
         const rc = system.open(file_path, flags, perm);
         switch (errno(rc)) {
diff --git a/lib/std/os/linux.zig b/lib/std/os/linux.zig
index 5631a90ef9..15f9bf9b62 100644
--- a/lib/std/os/linux.zig
+++ b/lib/std/os/linux.zig
@@ -492,7 +492,7 @@ pub fn renameat2(oldfd: i32, oldpath: [*:0]const u8, newfd: i32, newpath: [*:0]c
     );
 }
 
-pub fn open(path: [*:0]const u8, flags: u32, perm: usize) usize {
+pub fn open(path: [*:0]const u8, flags: u32, perm: mode_t) usize {
     if (@hasField(SYS, "open")) {
         return syscall3(.open, @ptrToInt(path), flags, perm);
     } else {
@@ -506,11 +506,11 @@ pub fn open(path: [*:0]const u8, flags: u32, perm: usize) usize {
     }
 }
 
-pub fn create(path: [*:0]const u8, perm: usize) usize {
+pub fn create(path: [*:0]const u8, perm: mode_t) usize {
     return syscall2(.creat, @ptrToInt(path), perm);
 }
 
-pub fn openat(dirfd: i32, path: [*:0]const u8, flags: u32, mode: usize) usize {
+pub fn openat(dirfd: i32, path: [*:0]const u8, flags: u32, mode: mode_t) usize {
     // dirfd could be negative, for example AT_FDCWD is -100
     return syscall4(.openat, @bitCast(usize, @as(isize, dirfd)), @ptrToInt(path), flags, mode);
 }