diff --git a/rules/siegen/nur-mit-pdf.json b/rules/siegen/nur-mit-pdf.json
index 05f51aa..d4bb3b0 100644
--- a/rules/siegen/nur-mit-pdf.json
+++ b/rules/siegen/nur-mit-pdf.json
@@ -6,7 +6,7 @@
         {
           "type": "list",
           "name": "ddb:transfer",
-          "expression": "grel:row.record.cells['ddb:transfer'].value.join('').contains('.pdf')",
+          "expression": "grel:row.record.cells['ddb:transfer'].value.join('').toLowercase().contains('.pdf')",
           "columnName": "ddb:transfer",
           "invert": false,
           "omitBlank": false,
diff --git a/rules/wuppertal/nbn.json b/rules/wuppertal/nbn.json
index 289aceb..2ef4da4 100644
--- a/rules/wuppertal/nbn.json
+++ b/rules/wuppertal/nbn.json
@@ -157,7 +157,7 @@
         {
           "type": "list",
           "name": "url",
-          "expression": "grel:row.record.cells['url'].value.join('').contains('.pdf')",
+          "expression": "grel:row.record.cells['url'].value.join('').toLowercase().contains('.pdf')",
           "columnName": "url",
           "invert": false,
           "omitBlank": false,