diff --git a/xen/include/asm-arm/types.h b/xen/include/asm-arm/types.h
index 48864f9..d2c5612 100644
--- a/xen/include/asm-arm/types.h
+++ b/xen/include/asm-arm/types.h
@@ -35,6 +35,7 @@ typedef u64 paddr_t;
 #define PRIpaddr "016llx"
 
 typedef unsigned long size_t;
+typedef long ssize_t;
 
 typedef char bool_t;
 #define test_and_set_bool(b)   xchg(&(b), 1)
diff --git a/xen/include/asm-x86/types.h b/xen/include/asm-x86/types.h
index 1c4c5d5..bb7ffc2 100644
--- a/xen/include/asm-x86/types.h
+++ b/xen/include/asm-x86/types.h
@@ -59,6 +59,12 @@ typedef char bool_t;
 #define test_and_set_bool(b)   xchg(&(b), 1)
 #define test_and_clear_bool(b) xchg(&(b), 0)
 
+#if defined(__i386__)
+typedef int ssize_t;
+#else /* __x86_64 */
+typedef long ssize_t;
+#endif
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* __X86_TYPES_H__ */