1 files changed, 3 insertions, 3 deletions
diff --git a/gr-blocks/lib/vco_c_impl.h b/gr-blocks/lib/vco_c_impl.h
index f2eab1621e..715cf6cad2 100644
--- a/gr-blocks/lib/vco_c_impl.h
+++ b/gr-blocks/lib/vco_c_impl.h
@@ -20,9 +20,9 @@ namespace blocks {
 class vco_c_impl : public vco_c
 {
 private:
-    double d_sampling_rate;
-    double d_sensitivity;
-    double d_amplitude;
+    const double d_sampling_rate;
+    const double d_sensitivity;
+    const double d_amplitude;
     double d_k;
     gr::fxpt_vco d_vco;