diff --git a/xen/Makefile b/xen/Makefile
index dd05672ff4..3a4e3bdd0f 100644
--- a/xen/Makefile
+++ b/xen/Makefile
@@ -599,7 +599,7 @@ cscope:
 	cscope -k -b -q
 
 .PHONY: _MAP
-_MAP:
+_MAP: $(TARGET)
 	$(NM) -n $(TARGET)-syms | grep -v '\(compiled\)\|\(\.o$$\)\|\( [aUw] \)\|\(\.\.ng$$\)\|\(LASH[RL]DI\)' > System.map
 
 %.o %.i %.s: %.c tools_fixdep FORCE