diff --git a/make/backup.mk b/make/backup.mk
index 8390fd2f..4fe5af92 100644
--- a/make/backup.mk
+++ b/make/backup.mk
@@ -4,9 +4,13 @@ BACKUP_DATE   ?= $(shell date +'%y%m%d-%H%M%S')
 
 _BACKUP_SOURCE = $(notdir $(shell cd $(BACKUP_SOURCE); $(PWD)))
 
+ifndef BACKUP_MK_INCLUDED
+BACKUP_MK_INCLUDED = true
+
 backup: distclean
 	tar -C .. $(_BACKUP_SOURCE) -cjf $(BACKUP_TARGET)/$(_BACKUP_SOURCE)-$(BACKUP_DATE).tar.bz2
 
 purge-last-backup:
 	$(RM) -f $(shell ls $(BACKUP_TARGET)/$(_BACKUP_SOURCE)-*.tar.bz2 | tail -1)
 
+endif # ifndef BACKUP_MK_INCLUDED
diff --git a/make/cpp-extra-targets.mk b/make/cpp-extra-targets.mk
index 2b71502b..5e1a5b19 100644
--- a/make/cpp-extra-targets.mk
+++ b/make/cpp-extra-targets.mk
@@ -1,4 +1,8 @@
+ifndef CPP_EXTRA_TARGETS_MK_INCLUDED
+CPP_EXTRA_TARGETS_MK_INCLUDED = true
+
 all:
 expand-macros:
 	make 2>/dev/null | sed '/$(CC)\|$(CPP)/ !d; s/$(CC)\|$(CPP)//; s/-o .*//' | grep -v "Wl\|rdynamic" | xargs $(CPP) -E -C | indent
 
+endif # ifndef CPP_EXTRA_TARGETS_MK_INCLUDED
diff --git a/make/dev-utils.mk b/make/dev-utils.mk
index 3a48faff..d5b7f9fd 100644
--- a/make/dev-utils.mk
+++ b/make/dev-utils.mk
@@ -1,3 +1,6 @@
+ifndef DEV_UTILS_MK_INCLUDED
+DEV_UTILS_MK_INCLUDED = true
+
 all:
 install:
 clean distclean:
@@ -20,4 +23,4 @@ install-to-system:
 		sudo systemctl restart $$s ;\
 	done
 
-
+endif # ifndef DEV_UTILS_MK_INCLUDED
diff --git a/make/targets-tools.mk b/make/targets-tools.mk
index 6420ff5f..667dca28 100644
--- a/make/targets-tools.mk
+++ b/make/targets-tools.mk
@@ -3,6 +3,9 @@
 # contact@jannet.de
 # $Id$
 
+ifndef TARGETS_TOOLS_MK_INCLUDED
+TARGETS_TOOLS_MK_INCLUDED = true
+
 include $(MODDIR)/make/rules.mk
 
 ifneq ($(strip $(SRC_ALL_CPP)),)
@@ -39,3 +42,4 @@ clean: objclean textclean localclean profclean clean.link
 clean.link:
 	if [ -L "$(HDRDIR_SCOPE_SUFFIX)" -a "`readlink $(HDRDIR_SCOPE_SUFFIX) 2>/dev/null`" = . ]; then rm $(HDRDIR_SCOPE_SUFFIX); fi
 
+endif # ifndef TARGETS_TOOLS_MK_INCLUDED