diff --git a/ttmath/ttmathparser.h b/ttmath/ttmathparser.h
index 4b49c04..f27f4bf 100644
--- a/ttmath/ttmathparser.h
+++ b/ttmath/ttmathparser.h
@@ -1975,7 +1975,7 @@ typename OperatorsTable::iterator iter_old, iter_new;
 		
 		if( iter_new == operators_table.end() || !IsSubstring(iter_new->first, oper) )
 		{
-			oper.pop_back(); // we've got mininum one element
+			oper.erase(oper.begin() + oper.size() - 1); // we've got mininum one element
 
 			if( iter_old != operators_table.end() && iter_old->first == oper )
 			{