diff --git a/lib_xua/api/xua_conf_default.h b/lib_xua/api/xua_conf_default.h
index 969336a5..d2908342 100644
--- a/lib_xua/api/xua_conf_default.h
+++ b/lib_xua/api/xua_conf_default.h
@@ -242,10 +242,6 @@
 #define AUDIO_CLASS_FALLBACK  0     /* Default to not falling back to UAC 1 */
 #endif
 
-#if defined(AUDIO_CLASS_FALLBACK) && (AUDIO_CLASS_FALLBACK==0)
-#undef AUDIO_CLASS_FALLBACK
-#endif
-
 /**
  * @brief Whether or not to run UAC2 in full-speed. When disabled device can either operate in
  *        UAC1 mode in full-speed (if AUDIO_CLASS_FALLBACK enabled) or return "null" descriptors.
@@ -254,7 +250,7 @@
  */
 #if (AUDIO_CLASS == 2)
     /* Whether to run in Audio Class 2.0 mode in USB Full-speed */
-    #if !defined(FULL_SPEED_AUDIO_2) && !defined(AUDIO_CLASS_FALLBACK)
+    #if !defined(FULL_SPEED_AUDIO_2) && (AUDIO_CLASS_FALLBACK == 0)
         #define FULL_SPEED_AUDIO_2    1     /* Default to falling back to UAC2 */
     #endif
 #endif
@@ -264,7 +260,7 @@
 #endif
 
 /* Some checks on full-speed functionality */
-#if defined(FULL_SPEED_AUDIO_2) && defined(AUDIO_CLASS_FALLBACK)
+#if defined(FULL_SPEED_AUDIO_2) && (AUDIO_CLASS_FALLBACK)
 #error FULL_SPEED_AUDIO_2 and AUDIO_CLASS_FALLBACK enabled!
 #endif
 
@@ -498,7 +494,7 @@
  *
  * Default: 0x0003
  */
-#if (AUDIO_CLASS==1) || defined(AUDIO_CLASS_FALLBACK) || defined(__DOXYGEN__)
+#if (AUDIO_CLASS == 1) || (AUDIO_CLASS_FALLBACK) || defined(__DOXYGEN__)
 #ifndef PID_AUDIO_1
 #define PID_AUDIO_1              (0x0003)
 #endif
diff --git a/lib_xua/src/core/endpoint0/xua_endpoint0.c b/lib_xua/src/core/endpoint0/xua_endpoint0.c
index 443ea44d..b3ef87a0 100755
--- a/lib_xua/src/core/endpoint0/xua_endpoint0.c
+++ b/lib_xua/src/core/endpoint0/xua_endpoint0.c
@@ -39,13 +39,13 @@
 
 /* Windows does not have a built in DFU driver (windows will prompt), so warn that DFU will not be functional in Audio 1.0 mode */
 #ifndef FORCE_UAC1_DFU
-#if ((AUDIO_CLASS==1) || defined(AUDIO_CLASS_FALLBACK)) && defined(DFU)
+#if ((AUDIO_CLASS == 1) || (AUDIO_CLASS_FALLBACK)) && defined(DFU)
 #warning DFU will not be enabled in AUDIO 1.0 mode due to Windows requesting driver
 #endif
 #endif
 
 /* MIDI not supported in Audio 1.0 mode */
-#if ((AUDIO_CLASS==1) || defined(AUDIO_CLASS_FALLBACK)) && defined(MIDI)
+#if ((AUDIO_CLASS == 1) || (AUDIO_CLASS_FALLBACK)) && defined(MIDI)
 #warning MIDI is currently not supported and will not be enabled in AUDIO 1.0 mode
 #endif
 
@@ -529,7 +529,7 @@ void XUA_Endpoint0(chanend c_ep0_out, chanend c_ep0_in, chanend c_audioControl,
 
                         if ((epNum == ENDPOINT_ADDRESS_OUT_AUDIO) || (epNum == ENDPOINT_ADDRESS_IN_AUDIO))
 				        {
-#if (AUDIO_CLASS == 2) && defined(AUDIO_CLASS_FALLBACK)
+#if (AUDIO_CLASS == 2) && (AUDIO_CLASS_FALLBACK)
                             if(g_curUsbSpeed == XUD_SPEED_FS)
                             {
                                 result = AudioEndpointRequests_1(ep0_out, ep0_in, &sp, c_audioControl, c_mix_ctl, c_clk_ctl);
@@ -594,7 +594,7 @@ void XUA_Endpoint0(chanend c_ep0_out, chanend c_ep0_in, chanend c_audioControl,
 #endif
                             )
                         {
-#if (AUDIO_CLASS == 2) && defined(AUDIO_CLASS_FALLBACK)
+#if (AUDIO_CLASS == 2) && (AUDIO_CLASS_FALLBACK)
                             if(g_curUsbSpeed == XUD_SPEED_HS)
                             {
                                 result = AudioClassRequests_2(ep0_out, ep0_in, &sp, c_audioControl, c_mix_ctl, c_clk_ctl);
@@ -645,7 +645,7 @@ void XUA_Endpoint0(chanend c_ep0_out, chanend c_ep0_in, chanend c_audioControl,
             if (!DFU_mode_active)
             {
 #endif
-#if defined(AUDIO_CLASS_FALLBACK) && (AUDIO_CLASS != 1)
+#if (AUDIO_CLASS_FALLBACK) && (AUDIO_CLASS != 1)
                 /* Return Audio 2.0 Descriptors with Audio 1.0 as fallback */
                 result = USB_StandardRequests(ep0_out, ep0_in,
                     (unsigned char*)&devDesc_Audio2, sizeof(devDesc_Audio2),
diff --git a/lib_xua/src/core/endpoint0/xua_ep0_descriptors.h b/lib_xua/src/core/endpoint0/xua_ep0_descriptors.h
index bafa8529..b8d02afd 100644
--- a/lib_xua/src/core/endpoint0/xua_ep0_descriptors.h
+++ b/lib_xua/src/core/endpoint0/xua_ep0_descriptors.h
@@ -1,6 +1,6 @@
 // Copyright (c) 2011-2018, XMOS Ltd, All rights reserved
 /**
- * @file    descriptors.h
+ * @file    xua_ep0_descriptors.h
  * @brief   Device Descriptors
  * @author  Ross Owen, XMOS Limited
 */
@@ -43,7 +43,7 @@ typedef struct
     STR_TABLE_ENTRY(usbInputTermStr_Audio2);      /* Users sees as output from host */
     STR_TABLE_ENTRY(usbOutputTermStr_Audio2);     /* User sees as input to host */
 #endif
-#if defined (AUDIO_CLASS_FALLBACK) || (AUDIO_CLASS == 1)
+#if  (AUDIO_CLASS_FALLBACK) || (AUDIO_CLASS == 1)
     /* Audio 1.0 Strings */
     STR_TABLE_ENTRY(productStr_Audio1);           /* Product string for Audio 1 */
     STR_TABLE_ENTRY(outputInterfaceStr_Audio1);   /* iInterface for streaming intefaces */
@@ -317,7 +317,7 @@ StringDescTable_t g_strTable =
     .usbInputTermStr_Audio2      = APPEND_PRODUCT_STR_A2(),
     .usbOutputTermStr_Audio2     = APPEND_PRODUCT_STR_A2(),
 #endif
-#if defined (AUDIO_CLASS_FALLBACK) || (AUDIO_CLASS == 1)
+#if (AUDIO_CLASS_FALLBACK) || (AUDIO_CLASS == 1)
     .productStr_Audio1           = PRODUCT_STR_A1,
     .outputInterfaceStr_Audio1   = APPEND_PRODUCT_STR_A1(),
     .inputInterfaceStr_Audio1    = APPEND_PRODUCT_STR_A1(),
@@ -392,7 +392,7 @@ StringDescTable_t g_strTable =
 
 /***** Device Descriptors *****/
 
-#if defined(AUDIO_CLASS_FALLBACK) || (AUDIO_CLASS==1)
+#if (AUDIO_CLASS_FALLBACK) || (AUDIO_CLASS == 1)
 /* Device Descriptor for Audio Class 1.0 (Assumes Full-Speed) */
 USB_Descriptor_Device_t devDesc_Audio1 =
 {
@@ -474,7 +474,7 @@ unsigned char devQualDesc_Audio2[] =
     0x00                            /* 9  bReserved (must be zero) */
 };
 
-#if defined(AUDIO_CLASS_FALLBACK) || (AUDIO_CLASS==1)
+#if (AUDIO_CLASS_FALLBACK) || (AUDIO_CLASS == 1)
 /* Device Qualifier Descriptor for running at high-speed (matches audio 1.0 device descriptor) */
 unsigned char devQualDesc_Audio1[] =
 {
@@ -2208,7 +2208,7 @@ unsigned char cfgDesc_Null[] =
 };
 
 
-#if defined (AUDIO_CLASS_FALLBACK) || (AUDIO_CLASS == 1)
+#if (AUDIO_CLASS_FALLBACK) || (AUDIO_CLASS == 1)
 /* Configuration descriptor for Audio v1.0 */
 /* Note Audio 1.0 descriptors still a simple array so we need some extra defines regarding lengths.. */
 #if (NUM_USB_CHAN_IN > 0)
diff --git a/lib_xua/src/core/endpoint0/xua_ep0_uacreqs.xc b/lib_xua/src/core/endpoint0/xua_ep0_uacreqs.xc
index db52c8e9..d10dc437 100644
--- a/lib_xua/src/core/endpoint0/xua_ep0_uacreqs.xc
+++ b/lib_xua/src/core/endpoint0/xua_ep0_uacreqs.xc
@@ -1069,7 +1069,7 @@ int AudioClassRequests_2(XUD_ep ep0_out, XUD_ep ep0_in, USB_SetupPacket_t &sp, c
 
 }
 
-#if defined (AUDIO_CLASS_FALLBACK) || (AUDIO_CLASS==1)
+#if (AUDIO_CLASS_FALLBACK != 0) || (AUDIO_CLASS == 1)
 
 int AudioEndpointRequests_1(XUD_ep ep0_out, XUD_ep ep0_in, USB_SetupPacket_t &sp, chanend c_audioControl, chanend ?c_mix_ctl, chanend ?c_clk_ctl)
 {
diff --git a/lib_xua/src/core/warnings.xc b/lib_xua/src/core/warnings.xc
index 7e071dbf..11ebb139 100644
--- a/lib_xua/src/core/warnings.xc
+++ b/lib_xua/src/core/warnings.xc
@@ -46,7 +46,7 @@ Warnings relating to configuration defines located in this XC source file rather
 #warning BCD_DEVICE not defined. Using XMOS release version number
 #endif
 
-#if (AUDIO_CLASS==1) || defined(AUDIO_CLASS_FALLBACK)
+#if (AUDIO_CLASS == 1) || (AUDIO_CLASS_FALLBACK)
 #ifndef PID_AUDIO_1
 #warning PID_AUDIO_1 not defined. Using 0x0003
 #endif