diff --git a/lib/std/c/openbsd.zig b/lib/std/c/openbsd.zig
index ab193abb6b..a1906bc9dd 100644
--- a/lib/std/c/openbsd.zig
+++ b/lib/std/c/openbsd.zig
@@ -28,9 +28,10 @@ pub const pthread_cond_t = extern struct {
 pub const pthread_spinlock_t = extern struct {
     inner: ?*c_void = null,
 };
-
 pub const pthread_attr_t = extern struct {
     inner: ?*c_void = null,
 };
 
+pub const sem_t = ?*opaque {};
+
 pub extern "c" fn posix_memalign(memptr: *?*c_void, alignment: usize, size: usize) c_int;