diff --git a/docs/design_guide.rst b/docs/design_guide.rst
index 1481caad74..1c0f5dbbd7 100644
--- a/docs/design_guide.rst
+++ b/docs/design_guide.rst
@@ -364,7 +364,7 @@ properties.
 +=======================+=======================+=========================================================================+
 | ``acceleration``      | (float, float, float) | x, y, z meter per second per second                                     |
 +-----------------------+-----------------------+-------------------------------------------------------------------------+
-| ``magnetic``          | float                 | micro-Tesla (uT)                                                        |
+| ``magnetic``          | (float, float, float) | micro-Tesla (uT)                                                        |
 +-----------------------+-----------------------+-------------------------------------------------------------------------+
 | ``orientation``       | (float, float, float) | x, y, z degrees                                                         |
 +-----------------------+-----------------------+-------------------------------------------------------------------------+