diff --git a/plugins/samplesink/hackrfoutput/hackrfoutput.cpp b/plugins/samplesink/hackrfoutput/hackrfoutput.cpp
index 9d4d2c6a2..fcab9d638 100644
--- a/plugins/samplesink/hackrfoutput/hackrfoutput.cpp
+++ b/plugins/samplesink/hackrfoutput/hackrfoutput.cpp
@@ -75,7 +75,7 @@ bool HackRFOutput::start(int device)
 //		qCritical("HackRFInput::start: failed to initiate HackRF library %s", hackrf_error_name(rc));
 //	}
 
-    m_sampleSourceFifo.resize(m_settings.m_devSampleRate); // 1s long
+    m_sampleSourceFifo.resize(m_settings.m_devSampleRate/2); // 500ms long
 
     if (m_deviceAPI->getSourceBuddies().size() > 0)
     {
diff --git a/plugins/samplesink/hackrfoutput/hackrfoutputthread.h b/plugins/samplesink/hackrfoutput/hackrfoutputthread.h
index cd84d0fe5..2bcbf63b7 100644
--- a/plugins/samplesink/hackrfoutput/hackrfoutputthread.h
+++ b/plugins/samplesink/hackrfoutput/hackrfoutputthread.h
@@ -25,7 +25,7 @@
 #include "dsp/samplesourcefifo.h"
 #include "dsp/interpolators.h"
 
-#define HACKRF_BLOCKSIZE (1<<18)
+#define HACKRF_BLOCKSIZE (1<<17)
 
 class HackRFOutputThread : public QThread {
 	Q_OBJECT