diff --git a/hw/sh_intc.c b/hw/sh_intc.c
index 7cd1fad..2369e8b 100644
--- a/hw/sh_intc.c
+++ b/hw/sh_intc.c
@@ -367,6 +367,10 @@ static void sh_intc_register_source(struct intc_desc *desc,
 	    for (k = 0; k < ARRAY_SIZE(mr->enum_ids); k++) {
 		if (mr->enum_ids[k] == source) {
 		    s->enable_max++;
+		    // Account for the fact that mask registers are
+		    // zero by default, and therefore don't mask
+		    // an interrupt by default.
+		    s->enable_count++;
 		    break;
 		}
 	    }
@@ -431,6 +435,7 @@ void sh_intc_register_sources(struct intc_desc *desc,
 
 		child = sh_intc_source(desc, gr->enum_ids[k]);
 		child->enable_max += s->enable_max;
+		child->enable_count += s->enable_count;
 	    }
 
 	    /* Chain sources within each group via source->next_enum_id,
@@ -537,3 +542,18 @@ void sh_intc_init_irl_priorities(struct intc_source *s)
 	s->priority = priority-- *2;
     assert(priority == 0);
 }
+
+void sh_intc_debug_lockup (struct intc_desc *desc)
+{
+  int i;
+  for (i = 0; i < desc->nr_sources; i++) 
+    {
+      struct intc_source *source = desc->sources + i;
+
+      if (source->asserted && !source->pending)
+	{
+	  printf ("source %d (%x) asserted, not pending, e = %d/%d\n",
+		  i, source->vect, source->enable_count, source->enable_max);
+	}
+    }
+}