diff --git a/src/net/sf/openrocket/database/Databases.java b/src/net/sf/openrocket/database/Databases.java
index 4652445a4..d8a132b02 100644
--- a/src/net/sf/openrocket/database/Databases.java
+++ b/src/net/sf/openrocket/database/Databases.java
@@ -1,6 +1,5 @@
 package net.sf.openrocket.database;
 
-import net.sf.openrocket.gui.util.SwingPreferences;
 import net.sf.openrocket.l10n.Translator;
 import net.sf.openrocket.logging.LogHelper;
 import net.sf.openrocket.material.Material;
@@ -96,7 +95,7 @@ public class Databases {
 		
 
 		// Add user-defined materials
-		for (Material m : ((SwingPreferences) Application.getPreferences()).getUserMaterials()) {
+		for (Material m : Application.getPreferences().getUserMaterials()) {
 			switch (m.getType()) {
 			case LINE:
 				LINE_MATERIAL.add(m);
diff --git a/src/net/sf/openrocket/material/MaterialStorage.java b/src/net/sf/openrocket/material/MaterialStorage.java
index 5438ece28..0d7f11b44 100644
--- a/src/net/sf/openrocket/material/MaterialStorage.java
+++ b/src/net/sf/openrocket/material/MaterialStorage.java
@@ -2,7 +2,6 @@ package net.sf.openrocket.material;
 
 import net.sf.openrocket.database.Database;
 import net.sf.openrocket.database.DatabaseListener;
-import net.sf.openrocket.gui.util.SwingPreferences;
 import net.sf.openrocket.startup.Application;
 
 /**
@@ -16,13 +15,13 @@ public class MaterialStorage implements DatabaseListener<Material> {
 	@Override
 	public void elementAdded(Material material, Database<Material> source) {
 		if (material.isUserDefined()) {
-			((SwingPreferences) Application.getPreferences()).addUserMaterial(material);
+			Application.getPreferences().addUserMaterial(material);
 		}
 	}
 
 	@Override
 	public void elementRemoved(Material material, Database<Material> source) {
-		((SwingPreferences) Application.getPreferences()).removeUserMaterial(material);
+		Application.getPreferences().removeUserMaterial(material);
 	}
 
 }
diff --git a/src/net/sf/openrocket/startup/Preferences.java b/src/net/sf/openrocket/startup/Preferences.java
index e728d396f..0a5e62b94 100644
--- a/src/net/sf/openrocket/startup/Preferences.java
+++ b/src/net/sf/openrocket/startup/Preferences.java
@@ -2,6 +2,7 @@ package net.sf.openrocket.startup;
 
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Set;
 
 import net.sf.openrocket.database.Databases;
 import net.sf.openrocket.l10n.Translator;
@@ -358,6 +359,10 @@ public abstract class Preferences {
 		return null;
 	}
 
+	public abstract void addUserMaterial(Material m);
+	public abstract Set<Material> getUserMaterials();
+	public abstract void removeUserMaterial(Material m);
+
 	/*
 	 * Map of default line styles
 	 */