diff --git a/components/sceneutil/shadow.cpp b/components/sceneutil/shadow.cpp
index 83a870f7fe..b9f2cbd831 100644
--- a/components/sceneutil/shadow.cpp
+++ b/components/sceneutil/shadow.cpp
@@ -13,7 +13,7 @@ namespace SceneUtil
 {
     using namespace osgShadow;
 
-    void ShadowManager::setupShadowSettings()
+    void ShadowManager::setupShadowSettings(Shader::ShaderManager& shaderManager)
     {
         mEnableShadows = Settings::Manager::getBool("enable shadows", "Shadows");
 
@@ -32,8 +32,7 @@ namespace SceneUtil
             = std::clamp(Settings::Manager::getInt("number of shadow maps", "Shadows"), 1, 8);
 
         mShadowSettings->setNumShadowMapsPerLight(numberOfShadowMapsPerLight);
-        mShadowSettings->setBaseShadowTextureUnit(
-            osg::GLExtensions::Get(0, false)->glMaxTextureUnits - numberOfShadowMapsPerLight);
+        mShadowSettings->setBaseShadowTextureUnit(shaderManager.reserveGlobalTextureUnits(Shader::ShaderManager::Slot::ShadowMaps, numberOfShadowMapsPerLight));
 
         const float maximumShadowMapDistance = Settings::Manager::getFloat("maximum shadow map distance", "Shadows");
         if (maximumShadowMapDistance > 0)
@@ -122,7 +121,7 @@ namespace SceneUtil
         mShadowedScene->setNodeMask(sceneRoot->getNodeMask());
 
         mShadowSettings = mShadowedScene->getShadowSettings();
-        setupShadowSettings();
+        setupShadowSettings(shaderManager);
 
         mShadowTechnique->setupCastingShader(shaderManager);
         mShadowTechnique->setWorldMask(worldMask);
diff --git a/components/sceneutil/shadow.hpp b/components/sceneutil/shadow.hpp
index c969ca331f..76fd2b7fdd 100644
--- a/components/sceneutil/shadow.hpp
+++ b/components/sceneutil/shadow.hpp
@@ -29,7 +29,7 @@ namespace SceneUtil
             Shader::ShaderManager& shaderManager);
         ~ShadowManager();
 
-        void setupShadowSettings();
+        void setupShadowSettings(Shader::ShaderManager& shaderManager);
 
         Shader::ShaderManager::DefineMap getShadowDefines();
 
diff --git a/components/shader/shadermanager.cpp b/components/shader/shadermanager.cpp
index 9f31412713..73290da2e3 100644
--- a/components/shader/shadermanager.cpp
+++ b/components/shader/shadermanager.cpp
@@ -636,31 +636,24 @@ namespace Shader
                 program->addShader(linkedShader);
     }
 
-    int ShaderManager::reserveGlobalTextureUnits(Slot slot)
+    int ShaderManager::reserveGlobalTextureUnits(Slot slot, int count)
     {
-        int unit = mReservedTextureUnitsBySlot[static_cast<int>(slot)];
-        if (unit >= 0)
-            return unit;
+        // TODO: Reuse units when count increase forces reallocation
+        // TODO: Warn if trampling on the ~8 units needed by model textures
+        auto unit = mReservedTextureUnitsBySlot[static_cast<int>(slot)];
+        if (unit.index >= 0 && unit.count >= count)
+            return unit.index;
 
-        {
-            // Texture units from `8 - numberOfShadowMaps` to `8` are used for shadows, so we skip them here.
-            // TODO: Maybe instead of fixed texture units use `reserveGlobalTextureUnits` for shadows as well.
-            static const int numberOfShadowMaps = Settings::Manager::getBool("enable shadows", "Shadows")
-                ? std::clamp(Settings::Manager::getInt("number of shadow maps", "Shadows"), 1, 8)
-                : 0;
-            if (getAvailableTextureUnits() >= 8 && getAvailableTextureUnits() - 1 < 8)
-                mReservedTextureUnits = mMaxTextureUnits - (8 - numberOfShadowMaps);
-        }
-
-        if (getAvailableTextureUnits() < 2)
+        if (getAvailableTextureUnits() < count + 1)
             throw std::runtime_error("Can't reserve texture unit; no available units");
-        mReservedTextureUnits++;
+        mReservedTextureUnits += count;
 
-        unit = mMaxTextureUnits - mReservedTextureUnits;
+        unit.index = mMaxTextureUnits - mReservedTextureUnits;
+        unit.count = count;
 
         mReservedTextureUnitsBySlot[static_cast<int>(slot)] = unit;
 
-        return unit;
+        return unit.index;
     }
 
     void ShaderManager::update(osgViewer::Viewer& viewer)
diff --git a/components/shader/shadermanager.hpp b/components/shader/shadermanager.hpp
index e057867ee3..f27c52a16e 100644
--- a/components/shader/shadermanager.hpp
+++ b/components/shader/shadermanager.hpp
@@ -76,9 +76,11 @@ namespace Shader
         {
             OpaqueDepthTexture,
             SkyTexture,
+            ShadowMaps,
+            SLOT_COUNT
         };
 
-        int reserveGlobalTextureUnits(Slot slot);
+        int reserveGlobalTextureUnits(Slot slot, int count = 1);
 
         void update(osgViewer::Viewer& viewer);
         void setHotReloadEnabled(bool value);
@@ -116,7 +118,8 @@ namespace Shader
         int mMaxTextureUnits = 0;
         int mReservedTextureUnits = 0;
         std::unique_ptr<HotReloadManager> mHotReloadManager;
-        std::array<int, 2> mReservedTextureUnitsBySlot = { -1, -1 };
+        struct ReservedTextureUnits { int index = -1; int count = 0; };
+        std::array<ReservedTextureUnits, static_cast<int>(Slot::SLOT_COUNT) > mReservedTextureUnitsBySlot = {};
     };
 
     bool parseForeachDirective(std::string& source, const std::string& templateName, size_t foundPos);