diff --git a/libraries/DataFlash/DataFlash_APM2.cpp b/libraries/DataFlash/DataFlash_APM2.cpp
index 3ef762ac66..f9cba3a067 100644
--- a/libraries/DataFlash/DataFlash_APM2.cpp
+++ b/libraries/DataFlash/DataFlash_APM2.cpp
@@ -95,9 +95,12 @@ unsigned char DataFlash_APM2::SPI_transfer(unsigned char data)
 {
     unsigned char retval;
 
-    // get spi3 semaphore if required.  if failed to get semaphore then just quietly fail
-    if( !AP_Semaphore_spi3.get(this) ) {
-        return 0;
+    // get spi3 semaphore if required.  if failed to get semaphore then
+    // just quietly fail
+    if ( _semaphore != NULL) {
+        if( !_semaphore->get(this) ) {
+            return 0;
+        }
     }
 
     /* Wait for empty transmit buffer */
@@ -110,7 +113,9 @@ unsigned char DataFlash_APM2::SPI_transfer(unsigned char data)
     retval = UDR3;
 
     // release spi3 semaphore
-    AP_Semaphore_spi3.release(this);
+    if ( _semaphore != NULL) {
+        _semaphore->release(this);
+    }
 
     return retval;
 }
@@ -127,11 +132,6 @@ void DataFlash_APM2::CS_active()
     digitalWrite(DF_SLAVESELECT,LOW);
 }
 
-// Constructors ////////////////////////////////////////////////////////////////
-DataFlash_APM2::DataFlash_APM2()
-{
-}
-
 // Public Methods //////////////////////////////////////////////////////////////
 void DataFlash_APM2::Init(void)
 {
diff --git a/libraries/DataFlash/DataFlash_APM2.h b/libraries/DataFlash/DataFlash_APM2.h
index 6c04070ef3..43ee446c24 100644
--- a/libraries/DataFlash/DataFlash_APM2.h
+++ b/libraries/DataFlash/DataFlash_APM2.h
@@ -4,7 +4,7 @@
 #ifndef __DATAFLASH_APM2_H__
 #define __DATAFLASH_APM2_H__
 
-#include <AP_Semaphore.h>       // for removing conflict with dataflash on SPI3 bus
+#include <AP_Semaphore.h>
 #include "DataFlash.h"
 
 class DataFlash_APM2 : public DataFlash_Class
@@ -27,8 +27,10 @@ private:
     void                    BlockErase (uint16_t BlockAdr);
     void                    ChipErase(void (*delay_cb)(unsigned long));
 
+    AP_Semaphore* _semaphore;
 public:
-    DataFlash_APM2();     // Constructor
+    DataFlash_APM2(AP_Semaphore* semaphore = NULL) : _semaphore(semaphore) {}
+
     void        Init();
     void        ReadManufacturerID();
     bool        CardInserted();