diff --git a/core/java/src/net/i2p/data/SimpleDataStructure.java b/core/java/src/net/i2p/data/SimpleDataStructure.java
index 441bcffac832773ae47ebddb02731a5a156d4bee..3983be17d2424aa36b46f54858028a5edb7511b3 100644
--- a/core/java/src/net/i2p/data/SimpleDataStructure.java
+++ b/core/java/src/net/i2p/data/SimpleDataStructure.java
@@ -81,7 +81,9 @@ public abstract class SimpleDataStructure extends DataStructureImpl {
         int length = length();
         _data = new byte[length];
         int read = read(in, _data);
-        if (read != length) throw new DataFormatException("Not enough bytes to read the data");
+        if (read != length)
+            throw new DataFormatException("EOF reading " + getClass().getSimpleName() +
+                                          ", read: " + read + ", required: " + length);
     }
     
     public void writeBytes(OutputStream out) throws DataFormatException, IOException {