--- a/src/hotspot/share/classfile/classFileParser.cpp	Wed Jun 27 12:46:15 2018 +0200
+++ b/src/hotspot/share/classfile/classFileParser.cpp	Wed Jun 27 09:52:23 2018 +0200
@@ -4612,12 +4612,17 @@
                                                       InstanceKlass::cast(super),
                                                       vca_result);
       if (msg == NULL) {
+        bool same_module = (this_klass->module() == super->module());
         Exceptions::fthrow(
           THREAD_AND_LOCATION,
           vmSymbols::java_lang_IllegalAccessError(),
-          "class %s cannot access its superclass %s",
+          "class %s cannot access its %ssuperclass %s (%s%s%s)",
           this_klass->external_name(),
-          super->external_name());
+          super->is_abstract() ? "abstract " : "",
+          super->external_name(),
+          (same_module) ? this_klass->joint_in_module_of_loader(super) : this_klass->class_in_module_of_loader(),
+          (same_module) ? "" : "; ",
+          (same_module) ? "" : super->class_in_module_of_loader());
       } else {
         // Add additional message content.
         Exceptions::fthrow(
@@ -4646,12 +4651,16 @@
                                                       InstanceKlass::cast(k),
                                                       vca_result);
       if (msg == NULL) {
+        bool same_module = (this_klass->module() == k->module());
         Exceptions::fthrow(
           THREAD_AND_LOCATION,
           vmSymbols::java_lang_IllegalAccessError(),
-          "class %s cannot access its superinterface %s",
+          "class %s cannot access its superinterface %s (%s%s%s)",
           this_klass->external_name(),
-          k->external_name());
+          k->external_name(),
+          (same_module) ? this_klass->joint_in_module_of_loader(k) : this_klass->class_in_module_of_loader(),
+          (same_module) ? "" : "; ",
+          (same_module) ? "" : k->class_in_module_of_loader());
       } else {
         // Add additional message content.
         Exceptions::fthrow(