diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_PX4.cpp b/libraries/AP_RangeFinder/AP_RangeFinder_PX4.cpp
index 0976f68a53..ae620f8bd8 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_PX4.cpp
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_PX4.cpp
@@ -62,6 +62,16 @@ AP_RangeFinder_PX4::AP_RangeFinder_PX4(RangeFinder &_ranger, uint8_t instance, R
     state.healthy = true;
 }
 
+/* 
+   close the file descriptor
+*/
+AP_RangeFinder_PX4::~AP_RangeFinder_PX4()
+{
+    if (_fd != -1) {
+        close(_fd);
+    }
+}
+
 /* 
    open the PX4 driver, returning the file descriptor
 */
diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_PX4.h b/libraries/AP_RangeFinder/AP_RangeFinder_PX4.h
index 4e953b4935..f096429c92 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_PX4.h
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_PX4.h
@@ -26,6 +26,9 @@ public:
     // constructor
     AP_RangeFinder_PX4(RangeFinder &ranger, uint8_t instance, RangeFinder::RangeFinder_State &_state);
 
+    // destructor
+    ~AP_RangeFinder_PX4(void);
+    
     // static detection function
     static bool detect(RangeFinder &ranger, uint8_t instance);