diff --git a/changelog/unreleased/issue-14373.toml b/changelog/unreleased/issue-14373.toml
new file mode 100644
index 000000000000..cbe6a5816aeb
--- /dev/null
+++ b/changelog/unreleased/issue-14373.toml
@@ -0,0 +1,5 @@
+type = "fixed"
+message = "Fix test lookup not accepting uppercase characters"
+
+issues = ["14373"]
+pulls = ["16909"]
diff --git a/graylog2-web-interface/src/components/lookup-tables/LookupTableView.tsx b/graylog2-web-interface/src/components/lookup-tables/LookupTableView.tsx
index 9fc9ca1f1830..2a29013ba7a1 100644
--- a/graylog2-web-interface/src/components/lookup-tables/LookupTableView.tsx
+++ b/graylog2-web-interface/src/components/lookup-tables/LookupTableView.tsx
@@ -50,7 +50,7 @@ const LookupTableView = ({ table, cache, dataAdapter }: Props) => {
     newValue.valid = event.target.value
                   && event.target.value.replace(/\s/g, '').length > 0;
 
-    newValue.value = event.target.value.toLowerCase();
+    newValue.value = event.target.value;
 
     switch (event.target.name) {
       case 'purgekey':