diff --git a/lib_xua/src/core/clocking/sw_pll_wrapper.h b/lib_xua/src/core/clocking/sw_pll_wrapper.h
index 74e1d51d..7b4e0236 100644
--- a/lib_xua/src/core/clocking/sw_pll_wrapper.h
+++ b/lib_xua/src/core/clocking/sw_pll_wrapper.h
@@ -1,6 +1,9 @@
 // Copyright 2024 XMOS LIMITED.
 // This Software is subject to the terms of the XMOS Public Licence: Version 1.
 
+#ifndef _SW_PLL_WRAPPPER_H_
+#define _SW_PLL_WRAPPPER_H_
+
 /* By default we use SW_PLL for Digital Rx configs running on XCORE-AI */
 /* Note: Not yet implemented for Synchronous mode */
 #ifdef __XS3A__
@@ -11,7 +14,7 @@
 #define USE_SW_PLL  0
 #endif /* __XS3A__ */
 
-
+#if USE_SW_PLL
 extern "C"
 {
     #include "sw_pll.h"
@@ -56,3 +59,6 @@ void do_sw_pll_phase_frequency_detector_dig_rx( unsigned short mclk_time_stamp,
  *  \param mClk     The current nominal mClk frequency.
  */
 unsigned InitSWPLL(sw_pll_state_t &sw_pll, unsigned mClk);
+
+#endif /* USE_SW_PLL */
+#endif /* _SW_PLL_WRAPPPER_H_ */
\ No newline at end of file
diff --git a/lib_xua/src/core/clocking/sw_pll_wrapper.xc b/lib_xua/src/core/clocking/sw_pll_wrapper.xc
index 3ac482a2..527016ac 100644
--- a/lib_xua/src/core/clocking/sw_pll_wrapper.xc
+++ b/lib_xua/src/core/clocking/sw_pll_wrapper.xc
@@ -5,12 +5,9 @@
 #include <print.h>
 
 #include "sw_pll_wrapper.h"
+#include "xua.h"
 
 #if USE_SW_PLL
-extern "C"
-{
-    #include "sw_pll.h"
-}
 
 /* Pointer to sw_pll struct to allow it to be used in separate SDM thread */ 
 unsafe 
@@ -212,4 +209,4 @@ void disable_sigma_delta(chanend c_sigma_delta)
     inuint(c_sigma_delta); /* Wait for ACK so we know reg write is complete */
 }
 
-#endif
+#endif /* USE_SW_PLL */