diff --git a/lib/std/os/bits/windows.zig b/lib/std/os/bits/windows.zig
index dbc42103ab..28a6a251f8 100644
--- a/lib/std/os/bits/windows.zig
+++ b/lib/std/os/bits/windows.zig
@@ -243,6 +243,7 @@ pub const IPPROTO_UDP = ws2_32.IPPROTO_UDP;
 pub const IPPROTO_ICMPV6 = ws2_32.IPPROTO_ICMPV6;
 pub const IPPROTO_RM = ws2_32.IPPROTO_RM;
 
+pub const nfds_t = c_ulong;
 pub const pollfd = ws2_32.pollfd;
 
 pub const POLLRDNORM = ws2_32.POLLRDNORM;
diff --git a/lib/std/os/windows.zig b/lib/std/os/windows.zig
index 1ed40e1f4f..f0530e53b2 100644
--- a/lib/std/os/windows.zig
+++ b/lib/std/os/windows.zig
@@ -1311,8 +1311,8 @@ pub fn recvfrom(s: ws2_32.SOCKET, buf: [*]u8, len: usize, flags: u32, from: ?*ws
     }
 }
 
-pub fn poll(fds: [*]ws2_32.pollfd, n: usize, timeout: i32) i32 {
-    return ws2_32.WSAPoll(fds, @intCast(u32, n), timeout);
+pub fn poll(fds: [*]ws2_32.pollfd, n: c_ulong, timeout: i32) i32 {
+    return ws2_32.WSAPoll(fds, n, timeout);
 }
 
 pub fn WSAIoctl(