diff --git a/tests/auto/corelib/text/qstring/tst_qstring.cpp b/tests/auto/corelib/text/qstring/tst_qstring.cpp
index 8d09cfa708..18fe85a338 100644
--- a/tests/auto/corelib/text/qstring/tst_qstring.cpp
+++ b/tests/auto/corelib/text/qstring/tst_qstring.cpp
@@ -3016,8 +3016,7 @@ void tst_QString::append_special_cases()
 
     {
         QString a = "onetwothree";
-        while (a.size() - 1)
-            a.remove(0, 1);
+        a.erase(a.cbegin(), std::prev(a.cend()));
         QCOMPARE(a.append(u'b'), QString("eb"));
     }
 }
@@ -3705,7 +3704,7 @@ void tst_QString::remove_extra()
         QString s = "BCDEFGHJK";
         QString s1 = s;
         s1.insert(0, u'A');  // detaches
-        s1.remove(0, 1);
+        s1.erase(s1.cbegin());
         QCOMPARE(s1, s);
     }
 
diff --git a/tests/auto/testlib/selftests/tst_selftests.cpp b/tests/auto/testlib/selftests/tst_selftests.cpp
index f6c97bc345..2265fe3147 100644
--- a/tests/auto/testlib/selftests/tst_selftests.cpp
+++ b/tests/auto/testlib/selftests/tst_selftests.cpp
@@ -459,11 +459,13 @@ BenchmarkResult BenchmarkResult::parse(QString const& line, QString* error)
     // This code avoids using a QRegExp because QRegExp might be broken.
     // Sample format: 4,000 msec per iteration (total: 4,000, iterations: 1)
 
-    QString sFirstNumber;
-    while (!remaining.isEmpty() && !remaining.at(0).isSpace()) {
-        sFirstNumber += remaining.at(0);
-        remaining.remove(0,1);
-    }
+    const auto begin = remaining.cbegin();
+    auto it = std::find_if(begin, remaining.cend(), [](const auto ch) {
+        return ch.isSpace();
+    });
+    QString sFirstNumber{std::distance(begin, it), Qt::Uninitialized};
+    std::move(begin, it, sFirstNumber.begin());
+    remaining.erase(begin, it);
     remaining = remaining.trimmed();
 
     // 4,000 -> 4000