diff -Nurd -x'*~' nut-2.7.4.orig/clients/Makefile.am nut-2.7.4/clients/Makefile.am
--- nut-2.7.4.orig/clients/Makefile.am	2015-12-29 07:08:34.000000000 -0500
+++ nut-2.7.4/clients/Makefile.am	2019-12-24 10:07:54.000000000 -0500
@@ -6,15 +6,15 @@
   LDADD += $(LIBSSL_LIBS)
 endif
 
-# Avoid per-target CFLAGS, because this will prevent re-use of object
+# Avoid per-target CPPFLAGS, because this will prevent re-use of object
 # files. In any case, CFLAGS are only -I options, so there is no harm,
 # but only add them if we really use the target.
-AM_CFLAGS = -I$(top_srcdir)/include
+AM_CPPFLAGS = -I$(top_srcdir)/include
 if WITH_SSL
-  AM_CFLAGS += $(LIBSSL_CFLAGS)
+  AM_CPPFLAGS += $(LIBSSL_CFLAGS)
 endif
 if WITH_CGI
-  AM_CFLAGS += $(LIBGD_CFLAGS)
+  AM_CPPFLAGS += $(LIBGD_CFLAGS)
 endif
 
 bin_PROGRAMS = upsc upslog upsrw upscmd
diff -Nurd -x'*~' nut-2.7.4.orig/common/Makefile.am nut-2.7.4/common/Makefile.am
--- nut-2.7.4.orig/common/Makefile.am	2015-12-29 07:08:34.000000000 -0500
+++ nut-2.7.4/common/Makefile.am	2019-12-24 10:01:36.000000000 -0500
@@ -1,6 +1,6 @@
 # Network UPS Tools: common
 
-AM_CFLAGS = -I$(top_srcdir)/include
+AM_CPPFLAGS = -I$(top_srcdir)/include
 
 noinst_LTLIBRARIES = libparseconf.la libcommon.la libcommonclient.la
 libparseconf_la_SOURCES = parseconf.c
diff -Nurd -x'*~' nut-2.7.4.orig/drivers/Makefile.am nut-2.7.4/drivers/Makefile.am
--- nut-2.7.4.orig/drivers/Makefile.am	2016-03-08 07:01:11.000000000 -0500
+++ nut-2.7.4/drivers/Makefile.am	2019-12-24 10:06:40.000000000 -0500
@@ -9,24 +9,24 @@
 
 # most targets are drivers, so make this the default
 LDADD = $(LDADD_DRIVERS_SERIAL)
-# Avoid per-target CFLAGS, because this will prevent re-use of object
-# files. In any case, CFLAGS are only -I options, so there is no harm,
+# Avoid per-target CPPFLAGS, because this will prevent re-use of object
+# files. In any case, CPPFLAGS are only -I options, so there is no harm,
 # but only add them if we really use the target.
-AM_CFLAGS = -I$(top_srcdir)/include
+AM_CPPFLAGS = -I$(top_srcdir)/include
 if WITH_USB
-  AM_CFLAGS += $(LIBUSB_CFLAGS)
+  AM_CPPFLAGS += $(LIBUSB_CFLAGS)
 endif
 if WITH_SNMP
-  AM_CFLAGS += $(LIBNETSNMP_CFLAGS)
+  AM_CPPFLAGS += $(LIBNETSNMP_CFLAGS)
 endif
 if WITH_NEON
-  AM_CFLAGS += $(LIBNEON_CFLAGS)
+  AM_CPPFLAGS += $(LIBNEON_CFLAGS)
 endif
 if WITH_LIBPOWERMAN
-  AM_CFLAGS += $(LIBPOWERMAN_CFLAGS)
+  AM_CPPFLAGS += $(LIBPOWERMAN_CFLAGS)
 endif
 if WITH_IPMI
-  AM_CFLAGS += $(LIBIPMI_CFLAGS)
+  AM_CPPFLAGS += $(LIBIPMI_CFLAGS)
 endif
 
 SERIAL_DRIVERLIST = al175 bcmxcp belkin belkinunv bestfcom	\
@@ -92,7 +92,7 @@
 upsdrvctl_SOURCES = upsdrvctl.c
 upsdrvctl_LDADD = $(LDADD_COMMON)
 
-# serial drivers: all of them use standard LDADD and CFLAGS
+# serial drivers: all of them use standard LDADD and CPPFLAGS
 al175_SOURCES = al175.c
 apcsmart_SOURCES = apcsmart.c apcsmart_tabs.c
 apcsmart_old_SOURCES = apcsmart-old.c
@@ -139,14 +139,14 @@
 riello_ser_SOURCES = riello.c riello_ser.c
 riello_ser_LDADD = $(LDADD) -lm
 
-# non-serial drivers: these use custom LDADD and/or CFLAGS
+# non-serial drivers: these use custom LDADD and/or CPPFLAGS
 
 # dummy
 dummy_ups_SOURCES = dummy-ups.c
-dummy_ups_CFLAGS = $(AM_CFLAGS) -I$(top_srcdir)/clients
+dummy_ups_CPPFLAGS = -I$(top_srcdir)/clients $(AM_CPPFLAGS)
 dummy_ups_LDADD = $(LDADD_DRIVERS) ../clients/libupsclient.la
 if WITH_SSL
-  dummy_ups_CFLAGS += $(LIBSSL_CFLAGS)
+  dummy_ups_CPPFLAGS += $(LIBSSL_CFLAGS)
   dummy_ups_LDADD += $(LIBSSL_LIBS)
 endif
 
@@ -156,7 +156,7 @@
 
 # apcupsd client driver
 apcupsd_ups_SOURCES = apcupsd-ups.c
-apcupsd_ups_CFLAGS = $(AM_CFLAGS)
+apcupsd_ups_CPPFLAGS = $(AM_CPPFLAGS)
 apcupsd_ups_LDADD = $(LDADD_DRIVERS)
 
 # sample skeleton driver
@@ -193,8 +193,8 @@
 
 # HID-over-serial
 mge_shut_SOURCES = usbhid-ups.c libshut.c libhid.c hidparser.c mge-hid.c
-# per-target CFLAGS are necessary here
-mge_shut_CFLAGS = $(AM_CFLAGS) -DSHUT_MODE
+# per-target CPPFLAGS are necessary here
+mge_shut_CPPFLAGS = $(AM_CPPFLAGS) -DSHUT_MODE
 mge_shut_LDADD = $(LDADD)
 
 # SNMP
@@ -231,13 +231,13 @@
 # nutdrv_qx USB/Serial
 nutdrv_qx_SOURCES = nutdrv_qx.c
 nutdrv_qx_LDADD = $(LDADD_DRIVERS) -lm
-nutdrv_qx_CFLAGS = $(AM_CFLAGS)
+nutdrv_qx_CPPFLAGS = $(AM_CPPFLAGS)
 if WITH_SERIAL
-nutdrv_qx_CFLAGS += -DQX_SERIAL
+nutdrv_qx_CPPFLAGS += -DQX_SERIAL
 nutdrv_qx_LDADD += $(SERLIBS) serial.o
 endif
 if WITH_USB
-nutdrv_qx_CFLAGS += -DQX_USB
+nutdrv_qx_CPPFLAGS += -DQX_USB
 nutdrv_qx_SOURCES += libusb.c usb-common.c
 nutdrv_qx_LDADD += $(LIBUSB_LIBS)
 endif
diff -Nurd -x'*~' nut-2.7.4.orig/server/Makefile.am nut-2.7.4/server/Makefile.am
--- nut-2.7.4.orig/server/Makefile.am	2015-12-29 07:08:34.000000000 -0500
+++ nut-2.7.4/server/Makefile.am	2019-12-24 10:04:35.000000000 -0500
@@ -3,12 +3,12 @@
 # Avoid per-target CFLAGS, because this will prevent re-use of object
 # files. In any case, CFLAGS are only -I options, so there is no harm,
 # but only add them if we really use the target.
-AM_CFLAGS = -I$(top_srcdir)/include
+AM_CPPFLAGS = -I$(top_srcdir)/include
 if WITH_WRAP
-  AM_CFLAGS += $(LIBWRAP_CFLAGS)
+  AM_CPPFLAGS += $(LIBWRAP_CFLAGS)
 endif
 if WITH_SSL
-  AM_CFLAGS += $(LIBSSL_CFLAGS)
+  AM_CPPFLAGS += $(LIBSSL_CFLAGS)
 endif
 LDADD = ../common/libcommon.la ../common/libparseconf.la $(NETLIBS)
 if WITH_WRAP
diff -Nurd -x'*~' nut-2.7.4.orig/tools/nut-scanner/Makefile.am nut-2.7.4/tools/nut-scanner/Makefile.am
--- nut-2.7.4.orig/tools/nut-scanner/Makefile.am	2015-12-29 07:08:34.000000000 -0500
+++ nut-2.7.4/tools/nut-scanner/Makefile.am	2019-12-24 10:07:10.000000000 -0500
@@ -17,30 +17,30 @@
 			../../common/common.c
 libnutscan_la_LIBADD = $(NETLIBS) $(LIBLTDL_LIBS)
 libnutscan_la_LDFLAGS = $(SERLIBS) -version-info 1:0:0
-libnutscan_la_CFLAGS = -I$(top_srcdir)/clients -I$(top_srcdir)/include $(LIBLTDL_CFLAGS) -I$(top_srcdir)/drivers
+libnutscan_la_CPPFLAGS = -I$(top_srcdir)/clients -I$(top_srcdir)/include $(LIBLTDL_CFLAGS) -I$(top_srcdir)/drivers
 
 nut_scanner_SOURCES = nut-scanner.c
-nut_scanner_CFLAGS = -I$(top_srcdir)/clients -I$(top_srcdir)/include
+nut_scanner_CPPFLAGS = -I$(top_srcdir)/clients -I$(top_srcdir)/include
 nut_scanner_LDADD = libnutscan.la ../../common/libcommon.la
 
 if WITH_SSL
-  libnutscan_la_CFLAGS += $(LIBSSL_CFLAGS)
+  libnutscan_la_CPPFLAGS += $(LIBSSL_CFLAGS)
   libnutscan_la_LIBADD += $(LIBSSL_LIBS)
 endif
 if WITH_USB
-  libnutscan_la_CFLAGS += $(LIBUSB_CFLAGS)
+  libnutscan_la_CPPFLAGS += $(LIBUSB_CFLAGS)
 endif
 if WITH_SNMP
-  libnutscan_la_CFLAGS += $(LIBNETSNMP_CFLAGS)
+  libnutscan_la_CPPFLAGS += $(LIBNETSNMP_CFLAGS)
 endif
 if WITH_NEON
-  libnutscan_la_CFLAGS += $(LIBNEON_CFLAGS)
+  libnutscan_la_CPPFLAGS += $(LIBNEON_CFLAGS)
 endif
 if WITH_AVAHI
-  libnutscan_la_CFLAGS += $(LIBAVAHI_CFLAGS)
+  libnutscan_la_CPPFLAGS += $(LIBAVAHI_CFLAGS)
 endif
 if WITH_IPMI
-  libnutscan_la_CFLAGS += $(LIBIPMI_CFLAGS)
+  libnutscan_la_CPPFLAGS += $(LIBIPMI_CFLAGS)
 endif
 
 dist_noinst_HEADERS = nutscan-usb.h nutscan-snmp.h