diff --git a/core/src/net/sf/openrocket/unit/Unit.java b/core/src/net/sf/openrocket/unit/Unit.java
index 4c4195b15..fd0f97ac6 100644
--- a/core/src/net/sf/openrocket/unit/Unit.java
+++ b/core/src/net/sf/openrocket/unit/Unit.java
@@ -90,8 +90,11 @@ public abstract class Unit {
 	 * @return       A string representation of the number in these units.
 	 */
 	public String toString(double value) {
-		double val = toUnit(value);
+		if (Double.isNaN(value))
+			return "N/A";
 		
+		double val = toUnit(value);
+
 		if (Math.abs(val) > 1E6) {
 			return expFormat.format(val);
 		}
diff --git a/swing/src/net/sf/openrocket/gui/dialogs/ComponentAnalysisDialog.java b/swing/src/net/sf/openrocket/gui/dialogs/ComponentAnalysisDialog.java
index b0b120c82..d05c0b039 100644
--- a/swing/src/net/sf/openrocket/gui/dialogs/ComponentAnalysisDialog.java
+++ b/swing/src/net/sf/openrocket/gui/dialogs/ComponentAnalysisDialog.java
@@ -571,7 +571,12 @@ public class ComponentAnalysisDialog extends JDialog implements StateChangeListe
 			}
 
 			if (forces.getCP() != null) {
-				row.cpx = forces.getCP().x;
+				if ((comp instanceof Rocket) &&
+					(forces.getCP().weight < MathUtil.EPSILON)) {
+					row.cpx = Double.NaN;
+				} else {
+					row.cpx = forces.getCP().x;
+				}
 				row.cna = forces.getCNa();
 			}