diff --git a/arch/sh/mm/pmb.c b/arch/sh/mm/pmb.c
index 3c9bf5b..a064830 100644
--- a/arch/sh/mm/pmb.c
+++ b/arch/sh/mm/pmb.c
@@ -77,7 +77,7 @@
 		if (pos < 0)
 			return ERR_PTR(pos);
 	} else {
-		if (test_bit(entry, &pmb_map))
+		if (test_and_set_bit(entry, &pmb_map))
 			return ERR_PTR(-ENOSPC);
 		pos = entry;
 	}