diff --git a/FMCTCSSRX.cpp b/FMCTCSSRX.cpp
index 5c36f66..6240f34 100644
--- a/FMCTCSSRX.cpp
+++ b/FMCTCSSRX.cpp
@@ -111,6 +111,8 @@ CTCSSState CFMCTCSSRX::process(q15_t sample)
 {
   m_result = m_result & (~CTS_READY);
 
+  q31_t samp = q31_t(sample);
+
   q31_t q2 = m_q1;
   m_q1 = m_q0;