diff --git a/apps/web/src/app/(portal)/modules/cert-manager/actions.ts b/apps/web/src/app/(portal)/modules/cert-manager/actions.ts
index 68195ba..6a475e0 100644
--- a/apps/web/src/app/(portal)/modules/cert-manager/actions.ts
+++ b/apps/web/src/app/(portal)/modules/cert-manager/actions.ts
@@ -151,7 +151,9 @@ export async function mergeCertsAction(
   password?: string,
 ): Promise<FileResponse> {
   const form = new FormData();
-  files.forEach((file) => form.append('files', file));
+  files.forEach((file) => {
+    form.append('files', file);
+  });
   form.append('outputFormat', outputFormat);
   if (password) form.append('password', password);
   return postForm('merge', form) as Promise<FileResponse>;
diff --git a/apps/web/src/app/(portal)/modules/dkv-fleet/components/InvoiceHistoryTable.tsx b/apps/web/src/app/(portal)/modules/dkv-fleet/components/InvoiceHistoryTable.tsx
index 53da372..64bb148 100644
--- a/apps/web/src/app/(portal)/modules/dkv-fleet/components/InvoiceHistoryTable.tsx
+++ b/apps/web/src/app/(portal)/modules/dkv-fleet/components/InvoiceHistoryTable.tsx
@@ -30,7 +30,7 @@ function formatDateTime(isoString: string): string {
   // new Date() never throws — it returns an Invalid Date object for bad input.
   // Check explicitly so malformed strings fall back gracefully instead of
   // rendering as "NaN.NaN.NaN, NaN:NaN Uhr" (WR-03).
-  if (isNaN(d.getTime())) return isoString;
+  if (Number.isNaN(d.getTime())) return isoString;
   const day = String(d.getDate()).padStart(2, '0');
   const month = String(d.getMonth() + 1).padStart(2, '0');
   const year = d.getFullYear();
diff --git a/apps/web/src/app/(portal)/modules/tender-radar/components/ResultsList.tsx b/apps/web/src/app/(portal)/modules/tender-radar/components/ResultsList.tsx
index 0bad2ea..550d1b0 100644
--- a/apps/web/src/app/(portal)/modules/tender-radar/components/ResultsList.tsx
+++ b/apps/web/src/app/(portal)/modules/tender-radar/components/ResultsList.tsx
@@ -48,7 +48,7 @@ interface TriageState {
 function formatDate(value: string | null): string {
   if (!value) return '–';
   const d = new Date(value);
-  if (isNaN(d.getTime())) return '–';
+  if (Number.isNaN(d.getTime())) return '–';
   return d.toLocaleDateString('de-DE');
 }
 
diff --git a/apps/web/src/app/(portal)/modules/tender-radar/components/TenderDetail.tsx b/apps/web/src/app/(portal)/modules/tender-radar/components/TenderDetail.tsx
index 7918587..f222a51 100644
--- a/apps/web/src/app/(portal)/modules/tender-radar/components/TenderDetail.tsx
+++ b/apps/web/src/app/(portal)/modules/tender-radar/components/TenderDetail.tsx
@@ -41,7 +41,7 @@ interface TenderDetailProps {
 function formatDeadline(value: string | null, noDeadlineLabel: string): string {
   if (!value) return noDeadlineLabel;
   const d = new Date(value);
-  if (isNaN(d.getTime())) return noDeadlineLabel;
+  if (Number.isNaN(d.getTime())) return noDeadlineLabel;
   return d.toLocaleDateString('de-DE');
 }
 
@@ -62,7 +62,7 @@ function formatValue(value: string | null, noValueLabel: string): string {
 
 function formatPublished(value: string): string {
   const d = new Date(value);
-  if (isNaN(d.getTime())) return '–';
+  if (Number.isNaN(d.getTime())) return '–';
   return d.toLocaleDateString('de-DE');
 }