diff --git a/mozilla/java/plugins/classes/org/mozilla/pluglet/mozilla/PlugletInputStream.java b/mozilla/java/plugins/classes/org/mozilla/pluglet/mozilla/PlugletInputStream.java
index f8e8b81c6ad..f4159b9cb70 100644
--- a/mozilla/java/plugins/classes/org/mozilla/pluglet/mozilla/PlugletInputStream.java
+++ b/mozilla/java/plugins/classes/org/mozilla/pluglet/mozilla/PlugletInputStream.java
@@ -50,6 +50,7 @@ public class PlugletInputStream extends InputStream {
     public synchronized void mark(int readlimit) {
     }
     public synchronized void reset() throws IOException {
+	throw new IOException("PlugletInputStream does not support mark");
     }
     public boolean markSupported() {
 	return false;