diff --git a/config.mk.in b/config.mk.in
index 958efdb3416..403d78e3798 100644
--- a/config.mk.in
+++ b/config.mk.in
@@ -76,6 +76,7 @@ MANFLAGS = \
 # https://www.gnu.org/software/automake/manual/1.16.5/html_node/User-Variables.html
 CC=@CC@
 CFLAGS=@CFLAGS@
+CPPFLAGS=@CPPFLAGS@
 LDFLAGS=@LDFLAGS@
 
 # Project variables
diff --git a/configure b/configure
index 6bc68741e14..767d1da00bb 100755
--- a/configure
+++ b/configure
@@ -5308,6 +5308,7 @@ cat <<EOF
 Compile options:
    CC: $CC
    CFLAGS: $CFLAGS
+   CPPFLAGS: $CPPFLAGS
    LDFLAGS: $LDFLAGS
    EXTRA_CFLAGS: $EXTRA_CFLAGS
    EXTRA_LDFLAGS: $EXTRA_LDFLAGS
diff --git a/configure.ac b/configure.ac
index fc99820de8c..d3b05d83978 100644
--- a/configure.ac
+++ b/configure.ac
@@ -276,6 +276,7 @@ cat <<EOF
 Compile options:
    CC: $CC
    CFLAGS: $CFLAGS
+   CPPFLAGS: $CPPFLAGS
    LDFLAGS: $LDFLAGS
    EXTRA_CFLAGS: $EXTRA_CFLAGS
    EXTRA_LDFLAGS: $EXTRA_LDFLAGS
diff --git a/src/prog.mk b/src/prog.mk
index b7ac597858d..426961c29c2 100644
--- a/src/prog.mk
+++ b/src/prog.mk
@@ -13,7 +13,7 @@ OBJS := $(SRCS:.c=.o) $(EXTRA_OBJS)
 all: $(TARGET)
 
 %.o : %.c $(HDRS) $(ROOT)/config.mk
-	$(CC) $(PROG_CFLAGS) $(CFLAGS) $(INCLUDE) -c $< -o $@
+	$(CC) $(PROG_CFLAGS) $(CFLAGS) $(CPPFLAGS) -c $< -o $@
 
 $(PROG): $(OBJS) $(ROOT)/config.mk
 	$(CC) $(PROG_LDFLAGS) $(LDFLAGS) -o $@ $(OBJS) $(LIBS)
diff --git a/src/so.mk b/src/so.mk
index c1913b79419..27c5695a8b3 100644
--- a/src/so.mk
+++ b/src/so.mk
@@ -13,7 +13,7 @@ OBJS := $(SRCS:.c=.o) $(EXTRA_OBJS)
 all: $(TARGET)
 
 %.o : %.c $(HDRS) $(ROOT)/config.mk
-	$(CC) $(SO_CFLAGS) $(CFLAGS) $(INCLUDE) -c $< -o $@
+	$(CC) $(SO_CFLAGS) $(CFLAGS) $(CPPFLAGS) -c $< -o $@
 
 $(SO): $(OBJS) $(ROOT)/config.mk
 	$(CC) $(SO_LDFLAGS) -shared $(LDFLAGS) -o $@ $(OBJS) -ldl