diff --git a/core/src/Variable/Variable.cpp b/core/src/Variable/Variable.cpp
index ca1c3cb..ed9c248 100644
--- a/core/src/Variable/Variable.cpp
+++ b/core/src/Variable/Variable.cpp
@@ -41,8 +41,11 @@ struct Variable::VariablePrivate {
             m_DataSeries->purge(m_CacheRange.m_TStart, m_CacheRange.m_TEnd);
         }
         updateRealRange();
+        updateNbPoints();
     }
 
+    void updateNbPoints() { m_NbPoints = m_DataSeries ? m_DataSeries->nbPoints() : 0; }
+
     /// Updates real range according to current variable range and data series
     void updateRealRange()
     {