diff --git a/lib/std/os/windows/ws2_32.zig b/lib/std/os/windows/ws2_32.zig
index 62b9a726fe..1fa5110b52 100644
--- a/lib/std/os/windows/ws2_32.zig
+++ b/lib/std/os/windows/ws2_32.zig
@@ -622,6 +622,7 @@ pub const AI_FILESERVER = 262144;
 pub const AI_DISABLE_IDN_ENCODING = 524288;
 pub const AI_EXTENDED = 2147483648;
 pub const AI_RESOLUTION_HANDLE = 1073741824;
+pub const FIONBIO = -2147195266;
 pub const ADDRINFOEX_VERSION_2 = 2;
 pub const ADDRINFOEX_VERSION_3 = 3;
 pub const ADDRINFOEX_VERSION_4 = 4;