diff --git a/src/insets/InsetTabular.cpp b/src/insets/InsetTabular.cpp
index 1b86dc316c..b4fef42542 100644
--- a/src/insets/InsetTabular.cpp
+++ b/src/insets/InsetTabular.cpp
@@ -3197,7 +3197,8 @@ void InsetTabular::updateLabels(Buffer const & buf, ParIterator const & it)
 
 	ParIterator it2 = it;
 	it2.forwardPos();
-	for ( ; it2.idx() <= it2.lastidx() ; it2.forwardIdx())
+	size_t const end = it2.nargs();
+	for ( ; it2.idx() < end; it2.forwardIdx())
 		lyx::updateLabels(buf, it2);
 
 	//reset afterwards