diff --git a/unix/syscall_darwin_amd64.go b/unix/syscall_darwin_amd64.go
index 7b0cb07e..db5a02dc 100644
--- a/unix/syscall_darwin_amd64.go
+++ b/unix/syscall_darwin_amd64.go
@@ -73,3 +73,7 @@ func sendfile(outfd int, infd int, offset *int64, count int) (written int, err e
 }
 
 func Syscall9(num, a1, a2, a3, a4, a5, a6, a7, a8, a9 uintptr) (r1, r2 uintptr, err syscall.Errno)
+
+// SYS___SYSCTL is used by syscall_bsd.go for all BSDs, but in modern versions
+// of darwin/amd64 the syscall is called sysctl instead of __sysctl.
+const SYS___SYSCTL = SYS_SYSCTL
diff --git a/unix/zsysnum_darwin_amd64.go b/unix/zsysnum_darwin_amd64.go
index 05de76aa..09de240c 100644
--- a/unix/zsysnum_darwin_amd64.go
+++ b/unix/zsysnum_darwin_amd64.go
@@ -141,7 +141,7 @@ const (
 	SYS_LSEEK                          = 199
 	SYS_TRUNCATE                       = 200
 	SYS_FTRUNCATE                      = 201
-	SYS___SYSCTL                       = 202
+	SYS_SYSCTL                         = 202
 	SYS_MLOCK                          = 203
 	SYS_MUNLOCK                        = 204
 	SYS_UNDELETE                       = 205