diff --git a/solr/solrj/src/java/org/apache/solr/client/solrj/io/eval/LowerEvaluator.java b/solr/solrj/src/java/org/apache/solr/client/solrj/io/eval/LowerEvaluator.java
index 1c5abfa6661..0fb5965677f 100644
--- a/solr/solrj/src/java/org/apache/solr/client/solrj/io/eval/LowerEvaluator.java
+++ b/solr/solrj/src/java/org/apache/solr/client/solrj/io/eval/LowerEvaluator.java
@@ -44,7 +44,7 @@ public class LowerEvaluator extends RecursiveObjectEvaluator implements OneValue
       return ((List<?>)value).stream().map(innerValue -> doWork(innerValue)).collect(Collectors.toList());
     }
     else{
-      return value.toString().toLowerCase();
+      return value.toString().toLowerCase(Locale.getDefault());
     }
   }
 }
diff --git a/solr/solrj/src/java/org/apache/solr/client/solrj/io/eval/UpperEvaluator.java b/solr/solrj/src/java/org/apache/solr/client/solrj/io/eval/UpperEvaluator.java
index 0624851d1c9..cc7f1d2625a 100644
--- a/solr/solrj/src/java/org/apache/solr/client/solrj/io/eval/UpperEvaluator.java
+++ b/solr/solrj/src/java/org/apache/solr/client/solrj/io/eval/UpperEvaluator.java
@@ -44,7 +44,7 @@ public class UpperEvaluator extends RecursiveObjectEvaluator implements OneValue
       return ((List<?>)value).stream().map(innerValue -> doWork(innerValue)).collect(Collectors.toList());
     }
     else{
-      return value.toString().toUpperCase();
+      return value.toString().toUpperCase(Locale.getDefault());
     }
   }
 }