diff --git a/tools/build/Makefile.build b/tools/build/Makefile.build
index 4a96473b180f938b038d5e698f3578876eb7c70c..ee566e8bd1cff56efde9200bf4a76caa840669f1 100644
--- a/tools/build/Makefile.build
+++ b/tools/build/Makefile.build
@@ -85,7 +85,7 @@ $(OUTPUT)%.i: %.c FORCE
 	$(call rule_mkdir)
 	$(call if_changed_dep,cc_i_c)
 
-$(OUTPUT)%.i: %.S FORCE
+$(OUTPUT)%.s: %.S FORCE
 	$(call rule_mkdir)
 	$(call if_changed_dep,cc_i_c)