diff --git a/xen/arch/arm/alternative.c b/xen/arch/arm/alternative.c
index 7203baed8a..2168393186 100644
--- a/xen/arch/arm/alternative.c
+++ b/xen/arch/arm/alternative.c
@@ -32,10 +32,6 @@
 #include <asm/insn.h>
 #include <asm/page.h>
 
-#define __ALT_PTR(a,f)      (u32 *)((void *)&(a)->f + (a)->f)
-#define ALT_ORIG_PTR(a)     __ALT_PTR(a, orig_offset)
-#define ALT_REPL_PTR(a)     __ALT_PTR(a, alt_offset)
-
 extern const struct alt_instr __alt_instructions[], __alt_instructions_end[];
 
 struct alt_region {
diff --git a/xen/common/livepatch.c b/xen/common/livepatch.c
index a6010eb00b..440e9141a3 100644
--- a/xen/common/livepatch.c
+++ b/xen/common/livepatch.c
@@ -621,8 +621,8 @@ static int prepare_payload(struct payload *payload,
 
         for ( a = start; a < end; a++ )
         {
-            const void *instr = &a->instr_offset + a->instr_offset;
-            const void *replacement = &a->repl_offset + a->repl_offset;
+            const void *instr = ALT_ORIG_PTR(a);
+            const void *replacement = ALT_REPL_PTR(a);
 
             if ( (instr < region->start && instr >= region->end) ||
                  (replacement < region->start && replacement >= region->end) )
diff --git a/xen/include/asm-arm/alternative.h b/xen/include/asm-arm/alternative.h
index 4287bac366..f25d3a7697 100644
--- a/xen/include/asm-arm/alternative.h
+++ b/xen/include/asm-arm/alternative.h
@@ -21,6 +21,11 @@ struct alt_instr {
 	u8  alt_len;		/* size of new instruction(s), <= orig_len */
 };
 
+/* Xen: helpers used by common code. */
+#define __ALT_PTR(a,f)		((u32 *)((void *)&(a)->f + (a)->f))
+#define ALT_ORIG_PTR(a)		__ALT_PTR(a, orig_offset)
+#define ALT_REPL_PTR(a)		__ALT_PTR(a, alt_offset)
+
 void __init apply_alternatives_all(void);
 int apply_alternatives(void *start, size_t length);
 
diff --git a/xen/include/asm-x86/alternative.h b/xen/include/asm-x86/alternative.h
index bce959f93f..63b036400d 100644
--- a/xen/include/asm-x86/alternative.h
+++ b/xen/include/asm-x86/alternative.h
@@ -23,6 +23,10 @@ struct alt_instr {
     u8  replacementlen;     /* length of new instruction, <= instrlen */
 };
 
+#define __ALT_PTR(a,f)      ((u8 *)((void *)&(a)->f + (a)->f))
+#define ALT_ORIG_PTR(a)     __ALT_PTR(a, instr_offset)
+#define ALT_REPL_PTR(a)     __ALT_PTR(a, repl_offset)
+
 /* Similar to apply_alternatives except it can be run with IRQs enabled. */
 extern void apply_alternatives_nocheck(struct alt_instr *start,
                                        struct alt_instr *end);