diff --git a/core/src/net/sf/openrocket/gui/customexpression/CustomExpressionPanel.java b/core/src/net/sf/openrocket/gui/customexpression/CustomExpressionPanel.java
index e0bd23608..7a7fb32a9 100644
--- a/core/src/net/sf/openrocket/gui/customexpression/CustomExpressionPanel.java
+++ b/core/src/net/sf/openrocket/gui/customexpression/CustomExpressionPanel.java
@@ -137,7 +137,7 @@ public class CustomExpressionPanel extends JPanel {
 				@Override
 				public void actionPerformed(ActionEvent e){
 					Window parent = SwingUtilities.getWindowAncestor(CustomExpressionPanel.this);
-					expression.editExpression(parent);
+					new ExpressionBuilderDialog(parent, expression.getSimulation(), expression).setVisible(true);
 					updateExpressions();
 				}
 			});
diff --git a/core/src/net/sf/openrocket/simulation/CustomExpression.java b/core/src/net/sf/openrocket/simulation/CustomExpression.java
index d060c07c2..1903079a2 100644
--- a/core/src/net/sf/openrocket/simulation/CustomExpression.java
+++ b/core/src/net/sf/openrocket/simulation/CustomExpression.java
@@ -1,11 +1,9 @@
 package net.sf.openrocket.simulation;
 
-import java.awt.Window;
 import java.util.SortedMap;
 import java.util.TreeMap;
 
 import net.sf.openrocket.document.Simulation;
-import net.sf.openrocket.gui.customexpression.ExpressionBuilderDialog;
 import net.sf.openrocket.logging.LogHelper;
 import net.sf.openrocket.startup.Application;
 import net.sf.openrocket.unit.FixedUnitGroup;
@@ -76,14 +74,6 @@ public class CustomExpression implements Cloneable{
 		setSimulation(sim);
 	}
 	
-	/*
-	 * Opens an ExpressionBuilderDialog for this expression 
-	 */
-	public void editExpression(Window parent){
-		log.debug("Opening window to edit an existing custom expression");
-		new ExpressionBuilderDialog(parent, sim, this).setVisible(true);
-	}
-	
 	/*
 	 * Use this to update the simulation this is associated with
 	 */
@@ -91,6 +81,10 @@ public class CustomExpression implements Cloneable{
 		CustomExpression.sim = sim;
 	}
 	
+	public Simulation getSimulation() {
+		return CustomExpression.sim;
+	}
+	
 	/*
 	 * Returns the flight data branch 0 for this simulation, or an empty branch
 	 * if no simulated data exists