diff --git a/mozilla/mailnews/base/src/nsMsgDBView.cpp b/mozilla/mailnews/base/src/nsMsgDBView.cpp
index a6c75474090..94f01113dea 100644
--- a/mozilla/mailnews/base/src/nsMsgDBView.cpp
+++ b/mozilla/mailnews/base/src/nsMsgDBView.cpp
@@ -4843,7 +4843,7 @@ nsresult nsMsgDBView::NavigateFromPos(nsMsgNavigationTypeValue motion, nsMsgView
             *pResultKey = m_keys.GetAt(*pResultIndex);
             break;
         case nsMsgNavigationType::previousMessage:
-            *pResultIndex = (startIndex != nsMsgViewIndex_None) ? startIndex - 1 : 0;
+            *pResultIndex = (startIndex != nsMsgViewIndex_None && startIndex > 0) ? startIndex - 1 : 0;
             *pResultKey = m_keys.GetAt(*pResultIndex);
             break;
         case nsMsgNavigationType::lastMessage: