diff -r 2b8512340180 -r bbb498ccb4ac src/Opcodes.cpp
--- a/src/Opcodes.cpp	Sat Dec 22 19:48:43 2012 -0800
+++ b/src/Opcodes.cpp	Sat Dec 22 23:18:57 2012 -0800
@@ -256,7 +256,7 @@
           {
             Heap::Tenure tenure = (Heap::Tenure)pc[1];
             StructMap *map = StructMap::cast(code->map(READ_UINT32(pc + 1)));
-            fprintf(fp, "%s", map->type()->name()->chars());
+            fprintf(fp, "%s", StructType::cast(map->type())->name()->chars());
             if (tenure == Heap::Tenure_Stack)
                 fprintf(fp, " ; lifo");
             else if (tenure == Heap::Tenure_Old)