1 files changed, 1 insertions, 1 deletions
diff --git a/gr-blocks/lib/probe_signal_v_impl.h b/gr-blocks/lib/probe_signal_v_impl.h
index d574bf7b17..6ee5ad7ad1 100644
--- a/gr-blocks/lib/probe_signal_v_impl.h
+++ b/gr-blocks/lib/probe_signal_v_impl.h
@@ -22,7 +22,7 @@ class probe_signal_v_impl : public probe_signal_v<T>
 {
 private:
     std::vector<T> d_level;
-    size_t d_size;
+    const size_t d_size;
 
 public:
     probe_signal_v_impl(size_t size);