diff --git a/smack-core/src/main/java/org/jivesoftware/smack/util/IpAddressUtil.java b/smack-core/src/main/java/org/jivesoftware/smack/util/IpAddressUtil.java
index 55586e2c3..8d1ad7b78 100644
--- a/smack-core/src/main/java/org/jivesoftware/smack/util/IpAddressUtil.java
+++ b/smack-core/src/main/java/org/jivesoftware/smack/util/IpAddressUtil.java
@@ -29,6 +29,8 @@ public class IpAddressUtil {
             return false;
         }
 
+        assert matcher.groupCount() == 4;
+
         for (int i = 1; i <= 4; i++) {
             String ipSegment = matcher.group(i);
             int ipSegmentInt;