diff --git a/imgsrv/lib/SRV/Utils.pm b/imgsrv/lib/SRV/Utils.pm
index fece35cce..8259e0071 100644
--- a/imgsrv/lib/SRV/Utils.pm
+++ b/imgsrv/lib/SRV/Utils.pm
@@ -503,9 +503,14 @@ sub parse_env {
             } else {
                 $value = join(',', @values);
             }
-            if ( ( $param eq 'seq' || $param eq 'seq[]' ) && ( $values[0] =~ m,^\d+$, || $values[0] =~ m{^\d+,\d+} || $values[0] =~ m{^\d+\-\d+} ) ) {
-              $value = "seq:" . join(',', sort { int($a) <=> int($b) } @values);
+            if ( $param eq 'seq' || $param eq 'seq[]' ) {
+              if ( $values[0] =~ m,^\d+$, || $values[0] =~ m{^\d+,\d+} || $values[0] =~ m{^\d+\-\d+} ) {
+                $value = "seq:" . join(',', sort { int($a) <=> int($b) } @values);
                 $key = 'file';
+              } else {
+                # Not a valid seq, remove it
+                next;
+              }
             }
             $$params{$key} = $value;
         }
diff --git a/pt/web/firebird/tests/imgsrv_download.spec.js b/pt/web/firebird/tests/imgsrv_download.spec.js
index 9e5e2c8c6..c6835a568 100644
--- a/pt/web/firebird/tests/imgsrv_download.spec.js
+++ b/pt/web/firebird/tests/imgsrv_download.spec.js
@@ -146,4 +146,11 @@ test.describe('imgsrv download', () => {
     expect(downloadHeaders['content-type']).toEqual('image/jpeg');
     expect(downloadBody.length).toBeGreaterThan(1);
   });
+
+  test('download pdf with bogus seq', async ({ request, page }) => {
+    const initialResponse = await request.get(
+      'http://apache:8080/cgi/imgsrv/download/pdf?id=test.pd_open&attachment=1&tracker=D1&seq=mashed_potatoes'
+    );
+    expect(initialResponse.status()).toEqual(200);
+  });
 });