diff --git a/src/gui/painting/qpainter.cpp b/src/gui/painting/qpainter.cpp
index 4e8e1d65ecf..f5285a9120f 100644
--- a/src/gui/painting/qpainter.cpp
+++ b/src/gui/painting/qpainter.cpp
@@ -6039,11 +6039,16 @@ static void drawTextItemDecoration(QPainter *painter, const QPointF &pos, const
         painter->fillRect(pos.x(), 0, qCeil(width), qMin(wave.height(), descent), wave);
         painter->restore();
     } else if (underlineStyle != QTextCharFormat::NoUnderline) {
+        const bool isAntialiasing = painter->renderHints().testFlag(QPainter::Antialiasing);
+        if (!isAntialiasing)
+            pen.setWidthF(qMax(fe->lineThickness().round(), QFixed(1)).toReal());
+        const qreal lineThicknessOffset = pen.widthF() / 2.0;
+
         // Deliberately ceil the offset to avoid the underline coming too close to
         // the text above it, but limit it to stay within descent.
-        qreal adjustedUnderlineOffset = std::ceil(underlineOffset) + 0.5;
+        qreal adjustedUnderlineOffset = std::ceil(underlineOffset) + lineThicknessOffset;
         if (underlineOffset <= fe->descent().toReal())
-            adjustedUnderlineOffset = qMin(adjustedUnderlineOffset, fe->descent().toReal() - qreal(0.5));
+            adjustedUnderlineOffset = qMin(adjustedUnderlineOffset, fe->descent().toReal() - lineThicknessOffset);
         const qreal underlinePos = pos.y() + adjustedUnderlineOffset;
         QColor uc = charFormat.underlineColor();
         if (uc.isValid())
@@ -6056,6 +6061,9 @@ static void drawTextItemDecoration(QPainter *painter, const QPointF &pos, const
             textEngine->addUnderline(painter, underline);
         else
             painter->drawLine(underline);
+
+        if (!isAntialiasing)
+            pen.setWidthF(fe->lineThickness().toReal());
     }
 
     pen.setStyle(Qt::SolidLine);
diff --git a/tests/baseline/painting/CMakeLists.txt b/tests/baseline/painting/CMakeLists.txt
index 86dc752186b..940967a9468 100644
--- a/tests/baseline/painting/CMakeLists.txt
+++ b/tests/baseline/painting/CMakeLists.txt
@@ -8,7 +8,8 @@
 # Collect test data
 file(GLOB_RECURSE test_data_glob
     RELATIVE ${CMAKE_CURRENT_SOURCE_DIR}
-    scripts/*)
+    scripts/*
+    fonts/* )
 list(APPEND test_data ${test_data_glob})
 
 if(NOT QT_BUILD_STANDALONE_TESTS AND NOT QT_BUILDING_QT)
diff --git a/tests/baseline/painting/fonts/QtUnderlineTest-Regular.ttf b/tests/baseline/painting/fonts/QtUnderlineTest-Regular.ttf
new file mode 100644
index 00000000000..0b165974abc
Binary files /dev/null and b/tests/baseline/painting/fonts/QtUnderlineTest-Regular.ttf differ
diff --git a/tests/baseline/painting/fonts/QtUnderlineTest2-Regular.ttf b/tests/baseline/painting/fonts/QtUnderlineTest2-Regular.ttf
new file mode 100644
index 00000000000..b830569a1a4
Binary files /dev/null and b/tests/baseline/painting/fonts/QtUnderlineTest2-Regular.ttf differ
diff --git a/tests/baseline/painting/scripts/text.qps b/tests/baseline/painting/scripts/text.qps
index 6bacdfd5e62..5f0576275e8 100644
--- a/tests/baseline/painting/scripts/text.qps
+++ b/tests/baseline/painting/scripts/text.qps
@@ -196,4 +196,30 @@ save
     drawText 0 20 "All the effects text drawing"
 restore
 
+translate 0 35
+save
+    setPen black
+    setFont "QtUnderlineTest" 20 normal normal default underline
+    drawText 0 20 "1234"
+restore
 
+translate 0 35.5
+save
+    setPen black
+    setFont "QtUnderlineTest2" 18 normal normal default underline
+    drawText 0 20 "1234"
+restore
+
+translate 0 35.5
+save
+    setPen black
+    setFont "QtUnderlineTest2" 12 normal normal default underline
+    drawText 0 20 "1234"
+restore
+
+translate 0 35.5
+save
+    setPen black
+    setFont "QtUnderlineTest2" 12 normal normal default underline
+    drawText 0 20 "1234"
+restore
diff --git a/tests/baseline/painting/tst_baseline_painting.cpp b/tests/baseline/painting/tst_baseline_painting.cpp
index d81f4468dcf..7e17926dc25 100644
--- a/tests/baseline/painting/tst_baseline_painting.cpp
+++ b/tests/baseline/painting/tst_baseline_painting.cpp
@@ -19,6 +19,8 @@
 #include <QOpenGLPaintDevice>
 #endif
 
+#include <QFontDatabase>
+
 #include <algorithm>
 
 #ifndef GL_RGB10
@@ -129,6 +131,16 @@ void tst_Lancelot::initTestCase()
         scriptChecksums.insert(fileName, qChecksum(cont));
     }
 
+    QString underlineTestFont1 = QFINDTESTDATA("fonts/QtUnderlineTest-Regular.ttf");
+    QVERIFY(!underlineTestFont1.isEmpty());
+    int id = QFontDatabase::addApplicationFont(underlineTestFont1);
+    QVERIFY(id >= 0);
+
+    QString underlineTestFont2 = QFINDTESTDATA("fonts/QtUnderlineTest2-Regular.ttf");
+    QVERIFY(!underlineTestFont2.isEmpty());
+    id = QFontDatabase::addApplicationFont(underlineTestFont2);
+    QVERIFY(id >= 0);
+
 #ifndef QT_NO_OPENGL
     initOpenGL();
 #endif