diff --git a/AdaptiveBrightness/monitor.hpp b/AdaptiveBrightness/monitor.hpp
index 21b9c30..bd6a368 100644
--- a/AdaptiveBrightness/monitor.hpp
+++ b/AdaptiveBrightness/monitor.hpp
@@ -2,7 +2,9 @@
 
 #ifdef _MSC_VER
 
+    #include <optional>
     #include <string>
+    #include <utility>
     #include <vector>
 
     #include <physicalmonitorenumerationapi.h>
@@ -46,6 +48,8 @@ class Monitor {
 
     const HMONITOR m_hMonitor;
     const PhysicalMonitor m_physicalMonitor;
+
+    std::optional<std::pair<DWORD, DWORD>> m_brightnessRange;
 };
 
 #endif
diff --git a/AdaptiveBrightness/monitor_win.cpp b/AdaptiveBrightness/monitor_win.cpp
index d800a6d..d0e469d 100644
--- a/AdaptiveBrightness/monitor_win.cpp
+++ b/AdaptiveBrightness/monitor_win.cpp
@@ -34,7 +34,35 @@ Monitor::~Monitor()
 
 bool Monitor::setBrightness(float percentage)
 {
-    return false;
+    if(!m_brightnessRange) {
+        qDebug(ltr("No brightness range known for monitor '%1' with handle '0x%2' and physical handle '0x%3'")
+                   .arg(m_physicalMonitor.name)
+                   .arg(reinterpret_cast<qulonglong>(m_hMonitor), 0, 16)
+                   .arg(reinterpret_cast<qulonglong>(m_physicalMonitor.handle), 0, 16));
+
+        if(std::isnan(getBrightness()))
+            return false;
+    }
+
+    const auto mappedBrightness = map(percentage, 0.f, 1.f, m_brightnessRange->first, m_brightnessRange->second);
+    const auto newBrightness = std::clamp<DWORD>(std::round(mappedBrightness), m_brightnessRange->first, m_brightnessRange->second);
+
+    if(!SetMonitorBrightness(m_physicalMonitor.handle, newBrightness)) {
+        qCritical(ltr("Failed to set brightness of monitor '%1' with handle '0x%2' and physical handle '0x%3', error: %4")
+                      .arg(m_physicalMonitor.name)
+                      .arg(reinterpret_cast<qulonglong>(m_hMonitor), 0, 16)
+                      .arg(reinterpret_cast<qulonglong>(m_physicalMonitor.handle), 0, 16)
+                      .arg(getLastErrorString()));
+        return false;
+    }
+
+    qDebug(ltr("Setting brightness of monitor '%1' with handle '0x%2' and physical handle '0x%3' to %4")
+               .arg(m_physicalMonitor.name)
+               .arg(reinterpret_cast<qulonglong>(m_hMonitor), 0, 16)
+               .arg(reinterpret_cast<qulonglong>(m_physicalMonitor.handle), 0, 16)
+               .arg(newBrightness));
+
+    return true;
 }
 
 float Monitor::getBrightness()
@@ -57,6 +85,8 @@ float Monitor::getBrightness()
         return NAN;
     }
 
+    m_brightnessRange = std::pair{minBrightness, maxBrightness};
+
     return std::clamp(map(brightness, minBrightness, maxBrightness, 0.f, 1.f), 0.f, 1.f);
 }