diff --git a/lib/std/c/netbsd.zig b/lib/std/c/netbsd.zig
index 1986d4e9bc40d7df1b1f7ef26b2a17c6656f0efb..23803144296aa01541ccc360f7d3e0716946ee1d 100644
--- a/lib/std/c/netbsd.zig
+++ b/lib/std/c/netbsd.zig
@@ -93,7 +93,7 @@ pub const pthread_rwlock_t = extern struct {
     wblocked_first: ?*u8 = null,
     wblocked_last: ?*u8 = null,
     nreaders: c_uint = 0,
-    owner: std.c.pthread_t = null,
+    owner: ?std.c.pthread_t = null,
     private: ?*anyopaque = null,
 };