diff --git a/motorApp/NewportSrc/drvXPSAsyn.c b/motorApp/NewportSrc/drvXPSAsyn.c
index 72b191f9..eb1e8654 100644
--- a/motorApp/NewportSrc/drvXPSAsyn.c
+++ b/motorApp/NewportSrc/drvXPSAsyn.c
@@ -612,6 +612,10 @@ static int motorAxisSetDouble(AXIS_HDL pAxis, motorAxisParam_t function, double
     double positions[XPS_MAX_AXES] = {0.0};
     
     if (pAxis == NULL) return MOTOR_AXIS_ERROR;
+    if (!pAxis->mutexId) {
+      PRINT(pAxis->logParam, MOTOR_ERROR, "motorAxisSetDouble[%d,%d]: invalid mutex ID. Call XPSConfigAxis first for initialization.\n", pAxis->card, pAxis->axis);
+      return MOTOR_AXIS_ERROR;
+    }
     else
     {
       if (epicsMutexLock( pAxis->mutexId ) == epicsMutexLockOK)
@@ -937,6 +941,11 @@ static int motorAxisMove(AXIS_HDL pAxis, double position, int relative,
 
     if (pAxis == NULL) return MOTOR_AXIS_ERROR;
 
+    if (!pAxis->mutexId) {
+      PRINT(pAxis->logParam, MOTOR_ERROR, "motorAxisMove[%d,%d]: invalid mutex ID. Call XPSConfigAxis first for initialization.\n", pAxis->card, pAxis->axis);
+      return MOTOR_AXIS_ERROR;
+    }
+
     PRINT(pAxis->logParam, FLOW, "Set card %d, axis %d move to %f, min vel=%f, max_vel=%f, accel=%f\n",
           pAxis->card, pAxis->axis, position, min_velocity, max_velocity, acceleration);