diff --git a/core/src/main/java/org/apache/ftpserver/ipfilter/RemoteIpFilter.java b/core/src/main/java/org/apache/ftpserver/ipfilter/RemoteIpFilter.java
index 8a1b036..6389ee6 100644
--- a/core/src/main/java/org/apache/ftpserver/ipfilter/RemoteIpFilter.java
+++ b/core/src/main/java/org/apache/ftpserver/ipfilter/RemoteIpFilter.java
@@ -216,7 +216,7 @@
             }
             return true;
         default:
-            throw new RuntimeException("Unknown or unimplemented filter type: "
+            throw new IllegalStateException("Unknown or unimplemented filter type: "
                     + type);
         }
     }