diff --git a/src/write.c b/src/write.c
index 46b82470..bddfad99 100644
--- a/src/write.c
+++ b/src/write.c
@@ -343,6 +343,9 @@ write_core(struct writer_control *p, pic_value obj)
   case PIC_TT_DICT:
     xfprintf(file, "#<dict %p>", pic_ptr(obj));
     break;
+  case PIC_TT_BLK:
+    xfprintf(file, "#<blk %p>", pic_ptr(obj));
+    break;
   }
 }