diff --git a/poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/BaseXSSFEvaluationWorkbook.java b/poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/BaseXSSFEvaluationWorkbook.java
index 01317d0c75..c2c1f06cd2 100644
--- a/poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/BaseXSSFEvaluationWorkbook.java
+++ b/poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/BaseXSSFEvaluationWorkbook.java
@@ -17,11 +17,10 @@
 
 package org.apache.poi.xssf.usermodel;
 
-import java.util.HashMap;
 import java.util.List;
-import java.util.Locale;
 import java.util.Map;
 
+import org.apache.commons.collections4.map.CaseInsensitiveMap;
 import org.apache.poi.ss.SpreadsheetVersion;
 import org.apache.poi.ss.formula.EvaluationName;
 import org.apache.poi.ss.formula.EvaluationWorkbook;
@@ -350,10 +349,6 @@ public abstract class BaseXSSFEvaluationWorkbook implements FormulaRenderingWork
         return _uBook.createName();
     }
 
-    private static String caseInsensitive(String s) {
-        return s.toUpperCase(Locale.ROOT);
-    }
-
     /*
      * TODO: data tables are stored at the workbook level in XSSF, but are bound to a single sheet.
      *       The current code structure has them hanging off XSSFSheet, but formulas reference them
@@ -369,13 +364,11 @@ public abstract class BaseXSSFEvaluationWorkbook implements FormulaRenderingWork
         if ( _tableCache != null ) {
             return _tableCache;
         }
-        // FIXME: use org.apache.commons.collections.map.CaseInsensitiveMap
-        _tableCache = new HashMap<>();
+        _tableCache = new CaseInsensitiveMap<>();
 
         for (Sheet sheet : _uBook) {
             for (XSSFTable tbl : ((XSSFSheet)sheet).getTables()) {
-                String lname = caseInsensitive(tbl.getName());
-                _tableCache.put(lname, tbl);
+                _tableCache.put(tbl.getName(), tbl);
             }
         }
         return _tableCache;
@@ -394,8 +387,7 @@ public abstract class BaseXSSFEvaluationWorkbook implements FormulaRenderingWork
     @Override
     public XSSFTable getTable(String name) {
         if (name == null) return null;
-        String lname = caseInsensitive(name);
-        return getTableCache().get(lname);
+        return getTableCache().get(name);
     }
 
     @Override
diff --git a/poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/XSSFTable.java b/poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/XSSFTable.java
index 1cff2e5f9c..39f45df8e3 100644
--- a/poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/XSSFTable.java
+++ b/poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/XSSFTable.java
@@ -25,9 +25,7 @@ import java.io.OutputStream;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
-import java.util.HashMap;
 import java.util.List;
-import java.util.Locale;
 
 import org.apache.commons.collections4.map.CaseInsensitiveMap;
 import org.apache.poi.ooxml.POIXMLDocumentPart;
@@ -817,10 +815,6 @@ public class XSSFTable extends POIXMLDocumentPart implements Table {
         commonXPath = null;
     }
 
-    private static String caseInsensitive(String s) {
-        return s.toUpperCase(Locale.ROOT);
-    }
-
     /**
      * Gets the relative column index of a column in this table having the header name {@code column}.
      * The column index is relative to the left-most column in the table, 0-indexed.
@@ -843,7 +837,7 @@ public class XSSFTable extends POIXMLDocumentPart implements Table {
             int i = 0;
             for (XSSFTableColumn column : getColumns()) {
                 String columnName = column.getName();
-                columnMap.put(caseInsensitive(columnName), i);
+                columnMap.put(columnName, i);
                 i++;
             }
         }