diff --git a/core/src/net/sf/openrocket/rocketcomponent/FinSet.java b/core/src/net/sf/openrocket/rocketcomponent/FinSet.java
index 4b8d58058..40aac2f90 100644
--- a/core/src/net/sf/openrocket/rocketcomponent/FinSet.java
+++ b/core/src/net/sf/openrocket/rocketcomponent/FinSet.java
@@ -440,7 +440,7 @@ public abstract class FinSet extends ExternalComponent {
 			
 			double da = (y0 + y1) * (x1 - x0) / 2;
 			finArea += da;
-			if (Math.abs(y0 - y1) < 0.00001) {
+			if (Math.abs(y0 + y1) < 0.00001) {
 				finCGx += (x0 + x1) / 2 * da;
 				finCGy += y0 / 2 * da;
 			} else {
diff --git a/core/test/net/sf/openrocket/rocketcomponent/FinSetTest.java b/core/test/net/sf/openrocket/rocketcomponent/FinSetTest.java
index 3ad01f852..881773e36 100644
--- a/core/test/net/sf/openrocket/rocketcomponent/FinSetTest.java
+++ b/core/test/net/sf/openrocket/rocketcomponent/FinSetTest.java
@@ -119,13 +119,13 @@ public class FinSetTest extends BaseTestCase {
 			fins.setPoints(points);
 			Coordinate coords = fins.getCG();
 			assertEquals(3.0, fins.getFinArea(), 0.001);
-			// FIXME - this computes NaN
-			//assertEquals(3.5/3.0, coords.x, 0.001);
-			//assertEquals(0.5/3.0, coords.y, 0.001);
+			assertEquals(3.5/3.0, coords.x, 0.001);
+			assertEquals(0.5/3.0, coords.y, 0.001);
 		}
 
 	}
 
+
 	@Test
 	public void testFreeformConvert() {
 		testFreeformConvert(new TrapezoidFinSet());