1 files changed, 1 insertions, 1 deletions
diff --git a/gr-blocks/lib/sub_impl.h b/gr-blocks/lib/sub_impl.h
index 97f4cf5156..6042c90bac 100644
--- a/gr-blocks/lib/sub_impl.h
+++ b/gr-blocks/lib/sub_impl.h
@@ -32,7 +32,7 @@ namespace blocks {
 template <class T>
 class BLOCKS_API sub_impl : public sub<T>
 {
-    size_t d_vlen;
+    const size_t d_vlen;
 
 public:
     sub_impl(size_t vlen);