diff --git a/poi-ooxml/src/main/java/org/apache/poi/xssf/model/SharedStringsTable.java b/poi-ooxml/src/main/java/org/apache/poi/xssf/model/SharedStringsTable.java
index b83f5f297e..dab4631371 100644
--- a/poi-ooxml/src/main/java/org/apache/poi/xssf/model/SharedStringsTable.java
+++ b/poi-ooxml/src/main/java/org/apache/poi/xssf/model/SharedStringsTable.java
@@ -124,8 +124,8 @@ public class SharedStringsTable extends POIXMLDocumentPart implements SharedStri
             int cnt = 0;
             _sstDoc = SstDocument.Factory.parse(is, DEFAULT_XML_OPTIONS);
             CTSst sst = _sstDoc.getSst();
-            count = (int)sst.getCount();
-            uniqueCount = (int)sst.getUniqueCount();
+            count = Math.toIntExact(sst.getCount());
+            uniqueCount = Math.toIntExact(sst.getUniqueCount());
             //noinspection deprecation
             for (CTRst st : sst.getSiArray()) {
                 stmap.put(xmlText(st), cnt);