diff --git a/header/ghostcp.go b/header/ghostcp.go
index f9dca81..c2f5b4f 100644
--- a/header/ghostcp.go
+++ b/header/ghostcp.go
@@ -165,7 +165,7 @@ func IPLookup(addr string) (IPConfig, bool) {
 			}
 		} else {
 			for i := 64; i >= 16; i -= 16 {
-				mask := net.CIDRMask(i, 32)
+				mask := net.CIDRMask(i, 128)
 				addr := fmt.Sprintf("%s/%d", ip.Mask(mask).String(), i)
 				config, ok = IPMap[addr]
 				if ok {
@@ -198,7 +198,7 @@ func IPBlockLookup(addr string) (IPConfig, bool) {
 		}
 	} else {
 		for i := 64; i >= 16; i -= 16 {
-			mask := net.CIDRMask(i, 32)
+			mask := net.CIDRMask(i, 128)
 			addr := fmt.Sprintf("%s/%d", ip.Mask(mask).String(), i)
 			config, ok = IPMap[addr]
 			if ok {