diff --git a/src/libxl/libxl_conf.h b/src/libxl/libxl_conf.h
index 24e172067b..ce2d69b0ac 100644
--- a/src/libxl/libxl_conf.h
+++ b/src/libxl/libxl_conf.h
@@ -52,6 +52,17 @@
 # define LIBXL_DUMP_DIR LIBXL_LIB_DIR "/dump"
 # define LIBXL_BOOTLOADER_PATH BINDIR "/pygrub"
 
+/* libxl interface for setting VCPU affinity changed in 4.5. In fact, a new
+ * parameter has been added, representative of 'VCPU soft affinity'. If one
+ * does not care about it (and that's libvirt case), passing NULL is the
+ * right thing to do. To mark that change, LIBXL_HAVE_VCPUINFO_SOFT_AFFINITY
+ * is defined. */
+# ifdef LIBXL_HAVE_VCPUINFO_SOFT_AFFINITY
+#  define libxl_set_vcpuaffinity(ctx, domid, vcpuid, map) \
+    libxl_set_vcpuaffinity((ctx), (domid), (vcpuid), (map), NULL)
+#  define libxl_set_vcpuaffinity_all(ctx, domid, max_vcpus, map) \
+    libxl_set_vcpuaffinity_all((ctx), (domid), (max_vcpus), (map), NULL)
+# endif
 
 typedef struct _libxlDriverPrivate libxlDriverPrivate;
 typedef libxlDriverPrivate *libxlDriverPrivatePtr;