diff --git a/libraries/AP_HAL_Linux/GPIO_Navigator.h b/libraries/AP_HAL_Linux/GPIO_Navigator.h
index 56ba66051f..1310c91d42 100644
--- a/libraries/AP_HAL_Linux/GPIO_Navigator.h
+++ b/libraries/AP_HAL_Linux/GPIO_Navigator.h
@@ -14,8 +14,9 @@ public:
     uint8_t read(uint8_t pin) override;
     void    write(uint8_t pin, uint8_t value) override;
 private:
-    uint8_t AllowedGPIOS[2] = {
-        RPI_GPIO_<26>(), // Aux Output for PWMs
+    uint8_t AllowedGPIOS[3] = {
+        RPI_GPIO_<18>(), // Aux Output for PWMs
+        RPI_GPIO_<26>(), // PCA OUTPUT_ENABLE
         RPI_GPIO_<27>()  // Leak detection
     };
     bool    pinAllowed(uint8_t pin);