diff --git a/reader/src/main/java/com/rusefi/can/reader/dbc/DbcFile.java b/reader/src/main/java/com/rusefi/can/reader/dbc/DbcFile.java
index cb57e0c..d763d55 100644
--- a/reader/src/main/java/com/rusefi/can/reader/dbc/DbcFile.java
+++ b/reader/src/main/java/com/rusefi/can/reader/dbc/DbcFile.java
@@ -98,8 +98,11 @@ public class DbcFile {
     }
 
     private void purgePacket(DbcPacket currentPacket) {
-        if (currentPacket != null)
+        if (currentPacket != null) {
+            if (packets.containsKey(currentPacket.getId()))
+                throw new IllegalStateException("We already have " + packets.get(currentPacket.getId()).getName() + " for " + currentPacket.getId());
             packets.put(currentPacket.getId(), currentPacket);
+        }
     }
 
     public static String replaceSpecialWithSpaces(String line) {