diff --git a/core/src/main/java/com/google/zxing/qrcode/detector/FinderPatternFinder.java b/core/src/main/java/com/google/zxing/qrcode/detector/FinderPatternFinder.java
index 17ca88b8f..0123f45db 100755
--- a/core/src/main/java/com/google/zxing/qrcode/detector/FinderPatternFinder.java
+++ b/core/src/main/java/com/google/zxing/qrcode/detector/FinderPatternFinder.java
@@ -695,7 +695,7 @@ public class FinderPatternFinder {
           // we need to check both two equal sides separately.
           // The value of |c^2 - 2 * b^2| + |c^2 - 2 * a^2| increases as dissimilarity
           // from isosceles right triangle.
-          double d = Math.abs(c - 2 * b) + Math.abs(c - 2 * a);
+          double d = Math.abs(c * c - 2 * b * b) + Math.abs(c * c - 2 * a * a);
           if (d < distortion) {
             distortion = d;
             bestPatterns[0] = fpi;
diff --git a/core/src/test/java/com/google/zxing/qrcode/QRCodeBlackBox3TestCase.java b/core/src/test/java/com/google/zxing/qrcode/QRCodeBlackBox3TestCase.java
index 9968608f8..c521ac5cb 100644
--- a/core/src/test/java/com/google/zxing/qrcode/QRCodeBlackBox3TestCase.java
+++ b/core/src/test/java/com/google/zxing/qrcode/QRCodeBlackBox3TestCase.java
@@ -29,8 +29,8 @@ public final class QRCodeBlackBox3TestCase extends AbstractBlackBoxTestCase {
     super("src/test/resources/blackbox/qrcode-3", new MultiFormatReader(), BarcodeFormat.QR_CODE);
     addTest(38, 38, 0.0f);
     addTest(39, 39, 90.0f);
-    addTest(36, 36, 180.0f);
-    addTest(39, 39, 270.0f);
+    addTest(33, 33, 180.0f);
+    addTest(38, 38, 270.0f);
   }
 
 }