diff --git a/luprex/Makefile b/luprex/Makefile
index 0396305a..e29e91f5 100644
--- a/luprex/Makefile
+++ b/luprex/Makefile
@@ -179,9 +179,9 @@ endif
 
 all: build/$(OS)/$(LUPREX_EXE) build/$(OS)/$(LUPREXSTATIC_EXE) build/$(OS)/$(LUPREXLIB_DLL)
 
-build/DIRECTORY:
+build/$(OS)/DIRECTORY:
 	mkdir -p build/$(OS)/core build/$(OS)/eris build/$(OS)/drv
-	touch build/DIRECTORY
+	touch build/$(OS)/DIRECTORY
 
 build/$(OS)/$(LUPREX_EXE): build/$(OS)/$(LUPREXLIB_DLL) $(OBJ_DRV)
 	$(LINKEXE) $@ $(OBJ_DRV) $(LIBS)
@@ -192,15 +192,15 @@ build/$(OS)/$(LUPREXSTATIC_EXE): $(OBJ_DRV) $(OBJ_ERIS) $(OBJ_CORE)
 build/$(OS)/$(LUPREXLIB_DLL): $(OBJ_ERIS) $(OBJ_CORE)
 	$(LINKDLL) $@ $^
 
-build/$(OS)/eris/%.obj: ext/eris-master/src/%.c build/DIRECTORY
+build/$(OS)/eris/%.obj: ext/eris-master/src/%.c build/$(OS)/DIRECTORY
 	$(MAKEDEPS) $@d $(LUA_FLAGS) $<
 	$(COMPILE) $@ $(LUA_FLAGS) $<
 
-build/$(OS)/core/%.obj: cpp/core/%.cpp build/DIRECTORY
+build/$(OS)/core/%.obj: cpp/core/%.cpp build/$(OS)/DIRECTORY
 	$(MAKEDEPS) $@d -I./ext/eris-master/src -I./cpp/wrap -I./cpp/core $<
 	$(COMPILE) $@ -I./ext/eris-master/src -I./cpp/wrap -I./cpp/core $<
 
-build/$(OS)/drv/%.obj: cpp/drv/%.cpp build/DIRECTORY
+build/$(OS)/drv/%.obj: cpp/drv/%.cpp build/$(OS)/DIRECTORY
 	$(MAKEDEPS) $@d $(OPENSSL_INCLUDE) -I./src/drv $<
 	$(COMPILE) $@ $(OPENSSL_INCLUDE) -I./src/drv $<