diff --git a/rpio.go b/rpio.go
index f2c9655..44e2b3a 100644
--- a/rpio.go
+++ b/rpio.go
@@ -304,5 +304,6 @@ func Open() (err error) {
 func Close() {
 	memlock.Lock()
 	syscall.Munmap(mem8)
+	syscall.Munmap(mem)
 	memlock.Unlock()
 }