diff --git a/camera_calibration/src/camera_calibration/camera_checker.py b/camera_calibration/src/camera_calibration/camera_checker.py
index 19149b5ec..a0d27a245 100755
--- a/camera_calibration/src/camera_calibration/camera_checker.py
+++ b/camera_calibration/src/camera_calibration/camera_checker.py
@@ -164,9 +164,9 @@ def handle_monocular(self, msg):
             image_points = C
             object_points = self.mc.mk_object_points([self.board], use_board_size=True)[0]
             dist_coeffs = numpy.zeros((4, 1))
-            camera_matrix = numpy.array( [ [ camera.P[0], camera.P[1], camera.P[2]  ],
-                                           [ camera.P[4], camera.P[5], camera.P[6]  ],
-                                           [ camera.P[8], camera.P[9], camera.P[10] ] ] )
+            camera_matrix = numpy.array( [ [ camera.p[0], camera.p[1], camera.p[2]  ],
+                                           [ camera.p[4], camera.p[5], camera.p[6]  ],
+                                           [ camera.p[8], camera.p[9], camera.p[10] ] ] )
             ok, rot, trans = cv2.solvePnP(object_points, image_points, camera_matrix, dist_coeffs)
             # Convert rotation into a 3x3 Rotation Matrix
             rot3x3, _ = cv2.Rodrigues(rot)