diff --git a/kcms/icons/package/contents/ui/IconSizePopup.qml b/kcms/icons/package/contents/ui/IconSizePopup.qml
--- a/kcms/icons/package/contents/ui/IconSizePopup.qml
+++ b/kcms/icons/package/contents/ui/IconSizePopup.qml
@@ -110,7 +110,7 @@
                 to: sizes.length - 1
                 stepSize: 1.0
                 snapMode: QtControls.Slider.SnapAlways
-                enabled: sizes.length > 0
+                enabled: sizes.length > 0 && !kcm.iconsSettings.isImmutable(iconTypeList.currentItem.configKey)
 
                 onMoved: {
                     kcm.iconsSettings[iconTypeList.currentItem.configKey] = iconSizeSlider.sizes[iconSizeSlider.value] || 0
diff --git a/kcms/icons/package/contents/ui/main.qml b/kcms/icons/package/contents/ui/main.qml
--- a/kcms/icons/package/contents/ui/main.qml
+++ b/kcms/icons/package/contents/ui/main.qml
@@ -36,8 +36,10 @@
     view.model: kcm.iconsModel
     view.currentIndex: kcm.pluginIndex(kcm.iconsSettings.theme)
     enabled: !kcm.downloadingFile
+    view.enabled: !kcm.iconsSettings.isImmutable("Theme")
 
     DropArea {
+        enabled: !kcm.iconsSettings.isImmutable("Theme")
         anchors.fill: parent
         onEntered: {
             if (!drag.hasUrls) {
@@ -242,13 +244,15 @@
             }
 
             QtControls.Button {
+                enabled: !kcm.iconsSettings.isImmutable("Theme")
                 id: installFromFileButton
                 text: i18n("Install from File...")
                 icon.name: "document-import"
                 onClicked: fileDialogLoader.active = true
             }
 
             QtControls.Button {
+                enabled: !kcm.iconsSettings.isImmutable("Theme")
                 text: i18n("Get New Icons...")
                 icon.name: "get-hot-new-stuff"
                 onClicked: kcm.getNewStuff(this)