diff --git a/aaa4j-radius-core/src/main/java/org/aaa4j/radius/core/packet/PacketCodec.java b/aaa4j-radius-core/src/main/java/org/aaa4j/radius/core/packet/PacketCodec.java
index 3ef4a08..73ef4de 100644
--- a/aaa4j-radius-core/src/main/java/org/aaa4j/radius/core/packet/PacketCodec.java
+++ b/aaa4j-radius-core/src/main/java/org/aaa4j/radius/core/packet/PacketCodec.java
@@ -545,13 +545,15 @@ private List<Attribute<?>> decodeAttributes(CodecContext codecContext, List<RawA
 
                 AttributeDefinition<?, ?> attributeDefinition = dictionary.getAttributeDefinition(nextType);
 
-                int numComplete = attributeDefinition.getAttributeCodec().decode(codecContext, attributeStack);
+                if (attributeDefinition != null) {
+                    int numComplete = attributeDefinition.getAttributeCodec().decode(codecContext, attributeStack);
 
-                for (int i = 0; i < numComplete; i++) {
-                    attributes.add(attributeStack.removeFirst());
-                }
+                    for (int i = 0; i < numComplete; i++) {
+                        attributes.add(attributeStack.removeFirst());
+                    }
 
-                continue;
+                    continue;
+                }
             }
 
             attributes.add(attributeStack.removeFirst());