diff --git a/Desktop_Interface/isobuffer.cpp b/Desktop_Interface/isobuffer.cpp
index b07c0cec..a62bb53d 100644
--- a/Desktop_Interface/isobuffer.cpp
+++ b/Desktop_Interface/isobuffer.cpp
@@ -1,6 +1,7 @@
 #include "isobuffer.h"
 
 #include <algorithm>
+#include <cassert>
 
 #include "isodriver.h"
 #include "uartstyledecoder.h"
@@ -121,6 +122,7 @@ std::unique_ptr<short[]> isoBuffer::readBuffer(double sampleWindow, int numSampl
     double itr = delaySamples;
     for (int i = 0; i < numSamples && itr < m_insertedCount; i++)
     {
+        assert(int(itr) >= 0);
         readData[i] = bufferAt(int(itr));
 
         if (singleBit)
diff --git a/Desktop_Interface/isodriver.cpp b/Desktop_Interface/isodriver.cpp
index f6d945b3..1e81ad9c 100644
--- a/Desktop_Interface/isodriver.cpp
+++ b/Desktop_Interface/isodriver.cpp
@@ -687,7 +687,13 @@ void isoDriver::frameActionGeneric(char CH1_mode, char CH2_mode)  //0 for off, 1
 
     double triggerDelay = 0;
     if (triggerEnabled)
+    {
         triggerDelay = (triggerMode < 2) ? internalBuffer375_CH1->getDelayedTriggerPoint(window) - window : internalBuffer375_CH2->getDelayedTriggerPoint(window) - window;
+
+        if (triggerDelay < 0)
+            triggerDelay = 0;
+    }
+
     if(singleShotEnabled && (triggerDelay != 0))
         singleShotTriggered(1);