$OpenBSD: patch-src_os_unix_unix_cpp,v 1.1 2012/12/25 00:17:37 bentley Exp $
--- src/os/unix/unix.cpp.orig	Sun Nov 18 01:13:52 2012
+++ src/os/unix/unix.cpp	Sun Nov 18 23:04:04 2012
@@ -38,6 +38,7 @@
 #endif
 
 #ifdef HAS_SYSCTL
+#include <sys/param.h>
 #include <sys/sysctl.h>
 #endif
 
@@ -337,9 +338,16 @@ uint GetCPUCoreCount()
 	int ncpu = 0;
 	size_t len = sizeof(ncpu);
 
+#if defined(__OpenBSD__)
+	int mib[2];
+	mib[0] = CTL_HW;
+	mib[1] = HW_NCPU;
+	sysctl(mib, 2, &ncpu, &len, NULL, 0);
+#else
 	if (sysctlbyname("hw.availcpu", &ncpu, &len, NULL, 0) < 0) {
 		sysctlbyname("hw.ncpu", &ncpu, &len, NULL, 0);
 	}
+#endif
 
 	if (ncpu > 0) count = ncpu;
 #elif defined(_SC_NPROCESSORS_ONLN)
