diff --git a/src/gui/painting/qcolorspace.cpp b/src/gui/painting/qcolorspace.cpp
index c98c31fe05..0f37ea19a0 100644
--- a/src/gui/painting/qcolorspace.cpp
+++ b/src/gui/painting/qcolorspace.cpp
@@ -53,6 +53,8 @@
 
 QT_BEGIN_NAMESPACE
 
+QBasicMutex QColorSpacePrivate::s_lutWriteLock;
+
 QColorSpacePrimaries::QColorSpacePrimaries(QColorSpace::Gamut gamut)
 {
     switch (gamut) {
diff --git a/src/gui/painting/qcolorspace_p.h b/src/gui/painting/qcolorspace_p.h
index a6ab2ab5cd..a49c46f195 100644
--- a/src/gui/painting/qcolorspace_p.h
+++ b/src/gui/painting/qcolorspace_p.h
@@ -56,8 +56,9 @@
 #include "qcolortrc_p.h"
 #include "qcolortrclut_p.h"
 
-#include <QtCore/qshareddata.h>
+#include <QtCore/qmutex.h>
 #include <QtCore/qpoint.h>
+#include <QtCore/qshareddata.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -112,8 +113,24 @@ public:
     QString description;
     QByteArray iccProfile;
 
-    mutable QSharedPointer<QColorTrcLut> lut[3];
-    mutable QAtomicInt lutsGenerated;
+    static QBasicMutex s_lutWriteLock;
+    struct LUT {
+        LUT() = default;
+        ~LUT() = default;
+        LUT(const LUT &other)
+        {
+            if (other.generated.loadAcquire()) {
+                table[0] = other.table[0];
+                table[1] = other.table[1];
+                table[2] = other.table[2];
+                generated.store(1);
+            }
+        }
+        QSharedPointer<QColorTrcLut> &operator[](int i) { return table[i]; }
+        const QSharedPointer<QColorTrcLut> &operator[](int i) const  { return table[i]; }
+        QSharedPointer<QColorTrcLut> table[3];
+        QAtomicInt generated;
+    } mutable lut;
 };
 
 QT_END_NAMESPACE
diff --git a/src/gui/painting/qcolortransform.cpp b/src/gui/painting/qcolortransform.cpp
index c723e12f8a..2f81449693 100644
--- a/src/gui/painting/qcolortransform.cpp
+++ b/src/gui/painting/qcolortransform.cpp
@@ -68,8 +68,12 @@ QColorTrcLut *lutFromTrc(const QColorTrc &trc)
 
 void QColorTransformPrivate::updateLutsIn() const
 {
-    if (colorSpaceIn->lutsGenerated.loadAcquire())
+    if (colorSpaceIn->lut.generated.loadAcquire())
         return;
+    QMutexLocker lock(&QColorSpacePrivate::s_lutWriteLock);
+    if (colorSpaceIn->lut.generated.load())
+        return;
+
     for (int i = 0; i < 3; ++i) {
         if (!colorSpaceIn->trc[i].isValid())
             return;
@@ -84,12 +88,15 @@ void QColorTransformPrivate::updateLutsIn() const
             colorSpaceIn->lut[i].reset(lutFromTrc(colorSpaceIn->trc[i]));
     }
 
-    colorSpaceIn->lutsGenerated.storeRelease(1);
+    colorSpaceIn->lut.generated.storeRelease(1);
 }
 
 void QColorTransformPrivate::updateLutsOut() const
 {
-    if (colorSpaceOut->lutsGenerated.loadAcquire())
+    if (colorSpaceOut->lut.generated.loadAcquire())
+        return;
+    QMutexLocker lock(&QColorSpacePrivate::s_lutWriteLock);
+    if (colorSpaceOut->lut.generated.load())
         return;
     for (int i = 0; i < 3; ++i) {
         if (!colorSpaceOut->trc[i].isValid())
@@ -105,7 +112,7 @@ void QColorTransformPrivate::updateLutsOut() const
             colorSpaceOut->lut[i].reset(lutFromTrc(colorSpaceOut->trc[i]));
     }
 
-    colorSpaceOut->lutsGenerated.storeRelease(1);
+    colorSpaceOut->lut.generated.storeRelease(1);
 }
 
 /*!
@@ -150,7 +157,7 @@ QRgb QColorTransform::map(const QRgb &argb) const
     c.x = std::max(0.0f, std::min(1.0f, c.x));
     c.y = std::max(0.0f, std::min(1.0f, c.y));
     c.z = std::max(0.0f, std::min(1.0f, c.z));
-    if (d->colorSpaceOut->lutsGenerated.loadAcquire()) {
+    if (d->colorSpaceOut->lut.generated.loadAcquire()) {
         c.x = d->colorSpaceOut->lut[0]->fromLinear(c.x);
         c.y = d->colorSpaceOut->lut[1]->fromLinear(c.y);
         c.z = d->colorSpaceOut->lut[2]->fromLinear(c.z);
@@ -182,7 +189,7 @@ QRgba64 QColorTransform::map(const QRgba64 &rgba64) const
     c.x = std::max(0.0f, std::min(1.0f, c.x));
     c.y = std::max(0.0f, std::min(1.0f, c.y));
     c.z = std::max(0.0f, std::min(1.0f, c.z));
-    if (d->colorSpaceOut->lutsGenerated.loadAcquire()) {
+    if (d->colorSpaceOut->lut.generated.loadAcquire()) {
         c.x = d->colorSpaceOut->lut[0]->fromLinear(c.x);
         c.y = d->colorSpaceOut->lut[1]->fromLinear(c.y);
         c.z = d->colorSpaceOut->lut[2]->fromLinear(c.z);
@@ -221,7 +228,7 @@ QColor QColorTransform::map(const QColor &color) const
     c = d->colorMatrix.map(c);
     bool inGamut = c.x >= 0.0f && c.x <= 1.0f && c.y >= 0.0f && c.y <= 1.0f && c.z >= 0.0f && c.z <= 1.0f;
     if (inGamut) {
-        if (d_ptr->colorSpaceOut->lutsGenerated.loadAcquire()) {
+        if (d_ptr->colorSpaceOut->lut.generated.loadAcquire()) {
             c.x = d->colorSpaceOut->lut[0]->fromLinear(c.x);
             c.y = d->colorSpaceOut->lut[1]->fromLinear(c.y);
             c.z = d->colorSpaceOut->lut[2]->fromLinear(c.z);