diff --git a/src/libs/utils/textutils.cpp b/src/libs/utils/textutils.cpp
index 9cb7c1e011f..a57e5310593 100644
--- a/src/libs/utils/textutils.cpp
+++ b/src/libs/utils/textutils.cpp
@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
 
 #include "textutils.h"
+#include "qtcassert.h"
 
 #include <QRegularExpression>
 #include <QTextBlock>
@@ -50,6 +51,7 @@ Position Position::fromFileName(QStringView fileName, int &postfixPos)
 
 Position Position::fromPositionInDocument(const QTextDocument *document, int pos)
 {
+    QTC_ASSERT(document, return {});
     const QTextBlock block = document->findBlock(pos);
     if (block.isValid())
         return {block.blockNumber() + 1, pos - block.position()};
diff --git a/tests/auto/utils/text/tst_text.cpp b/tests/auto/utils/text/tst_text.cpp
index 013c1d46c7c..3428b0b7576 100644
--- a/tests/auto/utils/text/tst_text.cpp
+++ b/tests/auto/utils/text/tst_text.cpp
@@ -3,6 +3,7 @@
 
 #include <utils/textutils.h>
 
+#include <QTextDocument>
 #include <QtTest>
 
 using namespace Utils::Text;
@@ -15,6 +16,9 @@ private slots:
     void testPositionFromFileName_data();
     void testPositionFromFileName();
 
+    void testPositionFromPositionInDocument_data();
+    void testPositionFromPositionInDocument();
+
     void testRangeLength_data();
     void testRangeLength();
 };
@@ -107,6 +111,30 @@ void tst_Text::testPositionFromFileName()
     QCOMPARE(postfixPos, expectedPostfixPos);
 }
 
+void tst_Text::testPositionFromPositionInDocument_data()
+{
+    QTest::addColumn<QString>("text");
+    QTest::addColumn<int>("documentPosition");
+    QTest::addColumn<Position>("position");
+
+    QTest::newRow("0") << QString() << 0 << Position{1, 0};
+    QTest::newRow("-1") << QString() << -1 << Position();
+    QTest::newRow("mid line") << QString("foo\n") << 1 << Position{1, 1};
+    QTest::newRow("second line") << QString("foo\n") << 4 << Position{2, 0};
+    QTest::newRow("second mid line") << QString("foo\nbar") << 5 << Position{2, 1};
+    QTest::newRow("behind content") << QString("foo\nbar") << 8 << Position();
+}
+
+void tst_Text::testPositionFromPositionInDocument()
+{
+    QFETCH(QString, text);
+    QFETCH(int, documentPosition);
+    QFETCH(Position, position);
+
+    const QTextDocument doc(text);
+    QCOMPARE(Position::fromPositionInDocument(&doc, documentPosition), position);
+}
+
 void tst_Text::testRangeLength_data()
 {
     QTest::addColumn<QString>("text");