diff --git a/module_usb_audio/usb_buffer/xc_ptr.h b/module_usb_audio/usb_buffer/xc_ptr.h
index 36b545c7..eeda3c9c 100644
--- a/module_usb_audio/usb_buffer/xc_ptr.h
+++ b/module_usb_audio/usb_buffer/xc_ptr.h
@@ -14,21 +14,21 @@ inline xc_ptr array_to_xc_ptr(const unsigned a[])
   return x;
 }
 
-#define write_via_xc_ptr(p,x)   asm("stw %0, %1[0]"::"r"(x),"r"(p))
+#define write_via_xc_ptr(p,x)               asm volatile("stw %0, %1[0]"::"r"(x),"r"(p))
 
-#define write_via_xc_ptr_indexed(p,i,x)   asm("stw %0, %1[%2]"::"r"(x),"r"(p),"r"(i))
-#define write_byte_via_xc_ptr_indexed(p,i,x)   asm("st8 %0, %1[%2]"::"r"(x),"r"(p),"r"(i))
+#define write_via_xc_ptr_indexed(p,i,x)     asm volatile("stw %0, %1[%2]"::"r"(x),"r"(p),"r"(i))
+#define write_byte_via_xc_ptr_indexed(p,i,x) asm volatile("st8 %0, %1[%2]"::"r"(x),"r"(p),"r"(i))
 // No immediate st8 format
-#define write_byte_via_xc_ptr(p,x)   write_byte_via_xc_ptr_indexed(p, 0, x)
+#define write_byte_via_xc_ptr(p,x)          write_byte_via_xc_ptr_indexed(p, 0, x)
 
-#define read_via_xc_ptr(x,p)  asm("ldw %0, %1[0]":"=r"(x):"r"(p));
+#define read_via_xc_ptr(x,p)                asm("ldw %0, %1[0]":"=r"(x):"r"(p));
 
-#define read_via_xc_ptr_indexed(x,p,i)  asm("ldw %0, %1[%2]":"=r"(x):"r"(p),"r"(i));
-#define read_byte_via_xc_ptr_indexed(x,p,i)  asm("ld8u %0, %1[%2]":"=r"(x):"r"(p),"r"(i));
+#define read_via_xc_ptr_indexed(x,p,i)      asm("ldw %0, %1[%2]":"=r"(x):"r"(p),"r"(i));
+#define read_byte_via_xc_ptr_indexed(x,p,i) asm("ld8u %0, %1[%2]":"=r"(x):"r"(p),"r"(i));
 // No immediate ld8u format
 #define read_byte_via_xc_ptr(x,p)  read_byte_via_xc_ptr_indexed(x, p, 0)
 
-#define GET_SHARED_GLOBAL(x, g) asm("ldw %0, dp[" #g "]":"=r"(x))
-#define SET_SHARED_GLOBAL(g, v) asm("stw %0, dp[" #g "]"::"r"(v))
+#define GET_SHARED_GLOBAL(x, g) asm volatile("ldw %0, dp[" #g "]":"=r"(x)::"memory")
+#define SET_SHARED_GLOBAL(g, v) asm volatile("stw %0, dp[" #g "]"::"r"(v):"memory")
 
 #endif