diff --git a/requirements.txt b/requirements.txt
index 02faab6..a1d35e7 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -13,7 +13,7 @@ cryptography==2.2.2
 enum34==1.1.6
 idna==2.6
 incremental==17.5.0
-ipaddress==1.0.19
+ipaddress==1.0.21
 lxml==4.2.1
 packaging==17.1
 pyasn1-modules==0.2.1