diff --git a/racket/src/rktio/rktio_cpu.c b/racket/src/rktio/rktio_cpu.c
index ca51fea3cc..807509e386 100644
--- a/racket/src/rktio/rktio_cpu.c
+++ b/racket/src/rktio/rktio_cpu.c
@@ -1,26 +1,18 @@
 #include "rktio.h"
 #include "rktio_private.h"
 
-#if defined(__linux__) || defined(__QNX__)
+#if defined(__linux__) || defined(__QNX__) || defined(OS_X) || defined(__FreeBSD__) || defined(__OpenBSD__)
 # include <unistd.h>
-#elif defined(OS_X)
-# include <sys/param.h>
-# include <sys/sysctl.h>
 #elif defined(RKTIO_SYSTEM_WINDOWS)
 # include <windows.h>
-#endif 
+#endif
 
 void rktio_init_cpu(rktio_t *rktio)
 {
   int processor_count;
-  
-#if defined(__linux__) || defined(__QNX__)
-  processor_count = sysconf(_SC_NPROCESSORS_ONLN);
-#elif defined(OS_X)
-  size_t size = sizeof(processor_count);
 
-  if (sysctlbyname("hw.ncpu", &processor_count, &size, NULL, 0))
-    processor_count = 2;
+#if defined(__linux__) || defined(__QNX__) || defined(OS_X) || defined(__FreeBSD__) || defined(__OpenBSD__)
+  processor_count = sysconf(_SC_NPROCESSORS_ONLN);
 #elif defined(RKTIO_SYSTEM_WINDOWS)
   SYSTEM_INFO sysinfo;
   GetSystemInfo(&sysinfo);