diff --git a/MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c b/MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c
index a9d7e3616e..c830db66a1 100644
--- a/MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c
+++ b/MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c
@@ -2397,7 +2397,7 @@ XhcGetElapsedTicks (
     // Counter counts upwards, check for an overflow condition
     //
     if (*PreviousTick > CurrentTick) {
-      Delta = (mXhciPerformanceCounterEndValue - *PreviousTick) + CurrentTick;
+      Delta = (CurrentTick - mXhciPerformanceCounterStartValue) + (mXhciPerformanceCounterEndValue - *PreviousTick);
     } else {
       Delta = CurrentTick - *PreviousTick;
     }
@@ -2406,7 +2406,7 @@ XhcGetElapsedTicks (
     // Counter counts downwards, check for an underflow condition
     //
     if (*PreviousTick < CurrentTick) {
-      Delta = (mXhciPerformanceCounterStartValue - CurrentTick) + *PreviousTick;
+      Delta = (mXhciPerformanceCounterStartValue - CurrentTick) + (*PreviousTick - mXhciPerformanceCounterEndValue);
     } else {
       Delta = *PreviousTick - CurrentTick;
     }