diff --git a/Makefile.inc b/Makefile.inc
index 1212dae..2b9d58d 100644
--- a/Makefile.inc
+++ b/Makefile.inc
@@ -520,7 +520,8 @@
 # Report new `build.ht` as dependency if `build.h` differs.
 build_h_check := \
 	export $(foreach exp,$(build_h_exports),$(exp)="$($(exp))"); \
-	util/genbuild_h/genbuild_h.sh .xcompile >$(build_h)t 2>/dev/null; \
+	util/genbuild_h/genbuild_h.sh $(xcompile) \
+		>$(build_h)t 2>/dev/null; \
 	cmp -s $(build_h)t $(build_h) >/dev/null 2>&1 || echo $(build_h)t
 
 $(build_h): $$(shell $$(build_h_check))