--- a/tests/protocol/tst_filehost.cpp
+++ b/tests/protocol/tst_filehost.cpp
@@ -36,6 +36,31 @@
                            .trimmed()
                            .toInt(&ok);
     return ok && raw.size() >= headerEnd + 4 + length;
+}
+
+// Qt 6.11 and earlier wrote header names in lowercase. Qt 6.12 uses the
+// canonical spelling, so match the name case-insensitively.
+bool wireHasHeader(const QByteArray &raw, const char *name, const QByteArray &value)
+{
+    const QByteArray expectedName = QByteArray(name).toLower();
+    const int headerEnd = raw.indexOf("\r\n\r\n");
+    const int limit = headerEnd < 0 ? raw.size() : headerEnd;
+    int start = 0;
+    while (start < limit) {
+        int end = raw.indexOf("\r\n", start);
+        if (end < 0 || end > limit)
+            end = limit;
+        const QByteArray line = raw.mid(start, end - start);
+        const int colon = line.indexOf(':');
+        if (colon > 0
+            && line.left(colon).trimmed().toLower() == expectedName
+            && line.mid(colon + 1).contains(value))
+            return true;
+        if (end >= limit)
+            break;
+        start = end + 2;
+    }
+    return false;
 }
 
 struct UploadCatcher
@@ -182,10 +207,10 @@
     QCOMPARE(ready.at(0).at(0).toString(),
              QStringLiteral("http://127.0.0.1:%1/upload/hoh5eFThae4e.txt")
                  .arg(server.serverPort()));
-    // Qt writes header names in lowercase.
-    QVERIFY(caught.captured.contains("authorization: Basic c2V1bmdoeWU6bm8="));
-    QVERIFY(caught.captured.contains("content-type: text/plain"));
-    QVERIFY(caught.captured.contains("content-disposition: attachment; filename=\"note.txt\""));
+    QVERIFY(wireHasHeader(caught.captured, "authorization", "Basic c2V1bmdoeWU6bm8="));
+    QVERIFY(wireHasHeader(caught.captured, "content-type", "text/plain"));
+    QVERIFY(wireHasHeader(caught.captured, "content-disposition",
+                          "attachment; filename=\"note.txt\""));
     QVERIFY(caught.captured.contains("hello file"));
 }
 
@@ -214,7 +239,7 @@
     QTRY_COMPARE(ready.size(), 1);
     const QByteArray header = QByteArray::fromStdString(
         basicAuthorizationValue("alice", "s3cret-token"));
-    QVERIFY(caught.captured.contains("authorization: " + header));
+    QVERIFY(wireHasHeader(caught.captured, "authorization", header));
     QVERIFY(!caught.captured.contains("s3cret-token"));
 }