Index: colorcorrection/manager.cpp
===================================================================
--- colorcorrection/manager.cpp
+++ colorcorrection/manager.cpp
@@ -25,6 +25,7 @@
 
 #include <main.h>
 #include <platform.h>
+#include <output.h>
 #include <screens.h>
 #include <workspace.h>
 #include <logind.h>
@@ -509,10 +510,10 @@
 
 void Manager::commitGammaRamps(int temperature)
 {
-    int nscreens = Screens::self()->count();
+    const auto outs = kwinApp()->platform()->outputs();
 
-    for (int screen = 0; screen < nscreens; screen++) {
-        int rampsize = kwinApp()->platform()->gammaRampSize(screen);
+    for (auto *o : outs) {
+        int rampsize = o->getGammaRampSize();
         GammaRamp ramp(rampsize);
 
         /*
@@ -542,13 +543,13 @@
             ramp.blue[i] = (double)ramp.blue[i] / (UINT16_MAX+1) * whitePoint[2] * (UINT16_MAX+1);
         }
 
-        if (kwinApp()->platform()->setGammaRamp(screen, ramp)) {
+        if (o->setGammaRamp(ramp)) {
             m_currentTemp = temperature;
             m_failedCommitAttempts = 0;
         } else {
             m_failedCommitAttempts++;
             if (m_failedCommitAttempts < 10) {
-                qCWarning(KWIN_COLORCORRECTION).nospace() << "Committing Gamma Ramp failed for screen " << screen <<
+                qCWarning(KWIN_COLORCORRECTION).nospace() << "Committing Gamma Ramp failed for output " << o->name() <<
                          ". Trying " << (10 - m_failedCommitAttempts) << " times more.";
             } else {
                 // TODO: On multi monitor setups we could try to rollback earlier changes for already commited outputs
Index: output.h
===================================================================
--- output.h
+++ output.h
@@ -45,6 +45,10 @@
 namespace KWin
 {
 
+namespace ColorCorrect {
+struct GammaRamp;
+}
+
 /**
  * Generic output representation in a Wayland session
  **/
@@ -89,6 +93,14 @@
         return m_waylandOutput;
     }
 
+    virtual int getGammaRampSize() const {
+        return 0;
+    }
+    virtual bool setGammaRamp(ColorCorrect::GammaRamp &gamma) {
+        Q_UNUSED(gamma);
+        return false;
+    }
+
 protected:
     QPointer<KWayland::Server::OutputChangeSet> changes() const {
         return m_changeset;
Index: platform.h
===================================================================
--- platform.h
+++ platform.h
@@ -42,7 +42,6 @@
 {
 namespace ColorCorrect {
 class Manager;
-struct GammaRamp;
 }
 
 class Output;
@@ -402,16 +401,6 @@
         return m_colorCorrect;
     }
 
-    virtual int gammaRampSize(int screen) const {
-        Q_UNUSED(screen);
-        return 0;
-    }
-    virtual bool setGammaRamp(int screen, ColorCorrect::GammaRamp &gamma) {
-        Q_UNUSED(screen);
-        Q_UNUSED(gamma);
-        return false;
-    }
-
     /*
      * A string of information to include in kwin debug output
      * It should not be translated.
Index: plugins/platforms/drm/drm_backend.h
===================================================================
--- plugins/platforms/drm/drm_backend.h
+++ plugins/platforms/drm/drm_backend.h
@@ -55,10 +55,6 @@
 namespace KWin
 {
 
-namespace ColorCorrect {
-struct GammaRamp;
-}
-
 class Udev;
 class UdevMonitor;
 
@@ -118,8 +114,6 @@
     gbm_device *gbmDevice() const {
         return m_gbmDevice;
     }
-    int gammaRampSize(int screen) const override;
-    bool setGammaRamp(int screen, ColorCorrect::GammaRamp &gamma) override;
 
     QVector<CompositingType> supportedCompositors() const override;
 
Index: plugins/platforms/drm/drm_backend.cpp
===================================================================
--- plugins/platforms/drm/drm_backend.cpp
+++ plugins/platforms/drm/drm_backend.cpp
@@ -31,7 +31,6 @@
 #include "screens_drm.h"
 #include "udev.h"
 #include "wayland_server.h"
-#include <colorcorrection/gammaramp.h>
 #if HAVE_GBM
 #include "egl_gbm_backend.h"
 #include <gbm.h>
@@ -780,24 +779,6 @@
 #endif
 }
 
-int DrmBackend::gammaRampSize(int screen) const
-{
-  if (m_outputs.size() <= screen) {
-      return 0;
-  }
-  auto *o = static_cast<DrmOutput*>(m_outputs.at(screen));
-  return o->m_crtc->getGammaRampSize();
-}
-
-bool DrmBackend::setGammaRamp(int screen, ColorCorrect::GammaRamp &gamma)
-{
-  if (m_outputs.size() <= screen) {
-      return false;
-  }
-  auto *o = static_cast<DrmOutput*>(m_outputs.at(screen));
-  return o->m_crtc->setGammaRamp(gamma);
-}
-
 QString DrmBackend::supportInformation() const
 {
     QString supportInfo;
Index: plugins/platforms/drm/drm_output.h
===================================================================
--- plugins/platforms/drm/drm_output.h
+++ plugins/platforms/drm/drm_output.h
@@ -136,6 +136,9 @@
     void transform(KWayland::Server::OutputDeviceInterface::Transform transform);
     void automaticRotation();
 
+    int getGammaRampSize() const override;
+    bool setGammaRamp(ColorCorrect::GammaRamp &gamma) override;
+
     DrmBackend *m_backend;
     DrmConnector *m_conn = nullptr;
     DrmCrtc *m_crtc = nullptr;
Index: plugins/platforms/drm/drm_output.cpp
===================================================================
--- plugins/platforms/drm/drm_output.cpp
+++ plugins/platforms/drm/drm_output.cpp
@@ -1264,4 +1264,14 @@
     emit screens()->changed();
 }
 
+int DrmOutput::getGammaRampSize() const
+{
+    return m_crtc->getGammaRampSize();
+}
+
+bool DrmOutput::setGammaRamp(ColorCorrect::GammaRamp &gamma)
+{
+    return m_crtc->setGammaRamp(gamma);
+}
+
 }
Index: plugins/platforms/virtual/virtual_backend.h
===================================================================
--- plugins/platforms/virtual/virtual_backend.h
+++ plugins/platforms/virtual/virtual_backend.h
@@ -69,8 +69,6 @@
     void setGbmDevice(gbm_device *device) {
         m_gbmDevice = device;
     }
-    virtual int gammaRampSize(int screen) const override;
-    virtual bool setGammaRamp(int screen, ColorCorrect::GammaRamp &gamma) override;
 
     QVector<CompositingType> supportedCompositors() const override {
         return QVector<CompositingType>{OpenGLCompositing, QPainterCompositing};
Index: plugins/platforms/virtual/virtual_backend.cpp
===================================================================
--- plugins/platforms/virtual/virtual_backend.cpp
+++ plugins/platforms/virtual/virtual_backend.cpp
@@ -138,15 +138,4 @@
     emit virtualOutputsSet(countChanged);
 }
 
-int VirtualBackend::gammaRampSize(int screen) const {
-    auto *out = qobject_cast<VirtualOutput*>(m_outputs[screen]);
-    return out->m_gammaSize;
-}
-
-bool VirtualBackend::setGammaRamp(int screen, ColorCorrect::GammaRamp &gamma) {
-    Q_UNUSED(gamma);
-    auto *out = qobject_cast<VirtualOutput*>(m_outputs[screen]);
-    return out->m_gammaResult;
-}
-
 }
Index: plugins/platforms/virtual/virtual_output.h
===================================================================
--- plugins/platforms/virtual/virtual_output.h
+++ plugins/platforms/virtual/virtual_output.h
@@ -41,6 +41,14 @@
 
     void setGeometry(const QRect &geo);
 
+    int getGammaRampSize() const override {
+        return m_gammaSize;
+    }
+    bool setGammaRamp(ColorCorrect::GammaRamp &gamma) override {
+        Q_UNUSED(gamma);
+        return m_gammaResult;
+    }
+
 private:
     Q_DISABLE_COPY(VirtualOutput);
     friend class VirtualBackend;