all:
        for DIR in $(SUBDIRS); do               \
-               BUILD_TARGET=$$OUTPUT/$$DIR;    \
+               BUILD_TARGET=$(OUTPUT)/$$DIR;   \
                mkdir $$BUILD_TARGET  -p;       \
                make OUTPUT=$$BUILD_TARGET -C $$DIR $@;\
        done
        install -t $(INSTALL_PATH) $(TEST_PROGS) $(TEST_PROGS_EXTENDED) $(TEST_FILES)
 
        @for SUBDIR in $(SUBDIRS); do \
-               BUILD_TARGET=$$OUTPUT/$$SUBDIR; \
+               BUILD_TARGET=$(OUTPUT)/$$SUBDIR;        \
                mkdir $$BUILD_TARGET  -p;       \
                $(MAKE) OUTPUT=$$BUILD_TARGET -C $$SUBDIR INSTALL_PATH=$(INSTALL_PATH)/$$SUBDIR install; \
        done;
 
 clean:
        for DIR in $(SUBDIRS); do               \
-               BUILD_TARGET=$$OUTPUT/$$DIR;    \
+               BUILD_TARGET=$(OUTPUT)/$$DIR;   \
                mkdir $$BUILD_TARGET  -p;       \
                make OUTPUT=$$BUILD_TARGET -C $$DIR $@;\
        done