Must check for markSupported on 1.3.1 VM's
diff --git a/bundles/org.eclipse.osgi/defaultAdaptor/src/org/eclipse/osgi/framework/adaptor/core/BundleURLConnection.java b/bundles/org.eclipse.osgi/defaultAdaptor/src/org/eclipse/osgi/framework/adaptor/core/BundleURLConnection.java
index b5345cd..5a83c52 100644
--- a/bundles/org.eclipse.osgi/defaultAdaptor/src/org/eclipse/osgi/framework/adaptor/core/BundleURLConnection.java
+++ b/bundles/org.eclipse.osgi/defaultAdaptor/src/org/eclipse/osgi/framework/adaptor/core/BundleURLConnection.java
@@ -71,7 +71,8 @@
 					}
 				}
 				try {
-					contentType = guessContentTypeFromStream(in);
+					if (in.markSupported())
+						contentType = guessContentTypeFromStream(in);
 				} catch (IOException e) {
 				}
 			}