diff --git a/unix/getdirentries_test.go b/unix/getdirentries_test.go
index 16250bd6..87819e70 100644
--- a/unix/getdirentries_test.go
+++ b/unix/getdirentries_test.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly
+// +build darwin dragonfly freebsd openbsd netbsd
 
 package unix_test
 
diff --git a/unix/syscall_netbsd.go b/unix/syscall_netbsd.go
index 8f4c320e..45377107 100644
--- a/unix/syscall_netbsd.go
+++ b/unix/syscall_netbsd.go
@@ -137,7 +137,7 @@ func Getdirentries(fd int, buf []byte, basep *uintptr) (n int, err error) {
 	if unsafe.Sizeof(*basep) == 8 {
 		return
 	}
-	if off>>4 != 0 {
+	if off>>32 != 0 {
 		// We can't stuff the offset back into a uintptr, so any
 		// future calls would be suspect. Generate an error.
 		// EIO is allowed by getdirentries.
diff --git a/unix/syscall_openbsd.go b/unix/syscall_openbsd.go
index 276c93be..4f34d6d0 100644
--- a/unix/syscall_openbsd.go
+++ b/unix/syscall_openbsd.go
@@ -106,7 +106,7 @@ func Getdirentries(fd int, buf []byte, basep *uintptr) (n int, err error) {
 	if unsafe.Sizeof(*basep) == 8 {
 		return
 	}
-	if off>>4 != 0 {
+	if off>>32 != 0 {
 		// We can't stuff the offset back into a uintptr, so any
 		// future calls would be suspect. Generate an error.
 		// EIO was allowed by getdirentries.