1 files changed, 3 insertions, 3 deletions
diff --git a/gr-blocks/lib/vco_f_impl.h b/gr-blocks/lib/vco_f_impl.h
index e6d727b128..11afe96919 100644
--- a/gr-blocks/lib/vco_f_impl.h
+++ b/gr-blocks/lib/vco_f_impl.h
@@ -20,9 +20,9 @@ namespace blocks {
 class vco_f_impl : public vco_f
 {
 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;