diff --git a/plugins/channelrx/demodais/aisdemodsink.cpp b/plugins/channelrx/demodais/aisdemodsink.cpp
index 55dee3fa1..9d8b5411e 100644
--- a/plugins/channelrx/demodais/aisdemodsink.cpp
+++ b/plugins/channelrx/demodais/aisdemodsink.cpp
@@ -199,7 +199,7 @@ void AISDemodSink::processOneSample(Complex &ci)
                 int sampleOffset = -1;
                 Real sampleSum = 0.0f;
                 for (int i = 0; i < sampleCnt; i++) {
-                    sampleSum += m_rxBuf[(x + sampleOffset + i) % m_rxBufLength] - dcOffset;
+                    sampleSum += m_rxBuf[(x + sampleOffset + i + m_rxBufLength) % m_rxBufLength] - dcOffset;
                 }
                 int symbol = sampleSum >= 0.0f ? 1 : 0;
 
diff --git a/plugins/channelrx/demodradiosonde/radiosondedemodsink.cpp b/plugins/channelrx/demodradiosonde/radiosondedemodsink.cpp
index a7d5cd0ff..16f02ade0 100644
--- a/plugins/channelrx/demodradiosonde/radiosondedemodsink.cpp
+++ b/plugins/channelrx/demodradiosonde/radiosondedemodsink.cpp
@@ -207,7 +207,7 @@ void RadiosondeDemodSink::processOneSample(Complex &ci)
                 int sampleOffset = -1;
                 Real sampleSum = 0.0f;
                 for (int i = 0; i < sampleCnt; i++) {
-                    sampleSum += m_rxBuf[(x + sampleOffset + i) % m_rxBufLength] - dcOffset;
+                    sampleSum += m_rxBuf[(x + sampleOffset + i + m_rxBufLength) % m_rxBufLength] - dcOffset;
                     sampleIdxs.append((x + sampleOffset + i) % m_rxBufLength);
                 }
                 int symbol = sampleSum >= 0.0f ? 1 : 0;