diff --git a/Config_Positioner.md b/Config_Positioner.md
index 0b7a65d..fb28a7d 100644
--- a/Config_Positioner.md
+++ b/Config_Positioner.md
@@ -28,6 +28,7 @@ The following settings are available for all types of positioners:
  **axisName**::<BR>
 &emsp;String value defines the name of the axis moved by this positioner.<BR>
 &emsp;Example: Coarse and Fine X both belong to SampleX.<BR>
+&emsp;Note: The named axis must be defined in axis.json, or Pixelator will crash.<BR>
 &emsp;**Default**: positioner name
 
  **nexus_name**::<BR>