diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 5086bb962b4dd9ca6471afb76f0698facb914816..7ea2e033d7153ad23de9dc02c0c0786abc1e11e2 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -736,10 +736,11 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
 		}
 	}
 	/*
-	 * The iftag must have been set somewhere because otherwise
-	 * we would return immediated at the beginning of the function
+	 * We need not to tag the root tag if there is no tag which is set with
+	 * settag within the range from *first_indexp to last_index.
 	 */
-	root_tag_set(root, settag);
+	if (tagged > 0)
+		root_tag_set(root, settag);
 	*first_indexp = index;
 
 	return tagged;