diff --git a/bundles/org.eclipse.e4.ui.workbench.swt/src/org/eclipse/e4/ui/internal/workbench/swt/CSSRenderingUtils.java b/bundles/org.eclipse.e4.ui.workbench.swt/src/org/eclipse/e4/ui/internal/workbench/swt/CSSRenderingUtils.java
index e0e73d027b6..ef291142027 100644
--- a/bundles/org.eclipse.e4.ui.workbench.swt/src/org/eclipse/e4/ui/internal/workbench/swt/CSSRenderingUtils.java
+++ b/bundles/org.eclipse.e4.ui.workbench.swt/src/org/eclipse/e4/ui/internal/workbench/swt/CSSRenderingUtils.java
@@ -59,7 +59,7 @@ public class CSSRenderingUtils {
 
 	// NOTE: The CSS engine 'owns' the image it returns (it caches it)
 	// so we have to cache any rotated versions to match
-	private Map<Image, Image> rotatedImageMap = new HashMap<>();
+	private final Map<Image, Image> rotatedImageMap = new HashMap<>();
 
 	public Control frameMeIfPossible(Control toFrame, String classId,
 			boolean vertical, boolean draggable) {
diff --git a/bundles/org.eclipse.e4.ui.workbench.swt/src/org/eclipse/e4/ui/internal/workbench/swt/PartRenderingEngine.java b/bundles/org.eclipse.e4.ui.workbench.swt/src/org/eclipse/e4/ui/internal/workbench/swt/PartRenderingEngine.java
index be6ec14fc17..cfcd37e51d0 100644
--- a/bundles/org.eclipse.e4.ui.workbench.swt/src/org/eclipse/e4/ui/internal/workbench/swt/PartRenderingEngine.java
+++ b/bundles/org.eclipse.e4.ui.workbench.swt/src/org/eclipse/e4/ui/internal/workbench/swt/PartRenderingEngine.java
@@ -122,11 +122,11 @@ public class PartRenderingEngine implements IPresentationEngine {
 
 	public static final String ENABLED_THEME_KEY = "themeEnabled";
 
-	private String factoryUrl;
+	private final String factoryUrl;
 
 	IRendererFactory curFactory = null;
 
-	private Map<String, AbstractPartRenderer> customRendererMap = new HashMap<>();
+	private final Map<String, AbstractPartRenderer> customRendererMap = new HashMap<>();
 
 	org.eclipse.swt.widgets.Listener keyListener;