diff -Naurp a/Makefile.in b/Makefile.in
--- a/Makefile.in	2013-09-18 12:48:43.000000000 +0000
+++ b/Makefile.in	2019-06-01 20:21:06.204864658 +0000
@@ -1,11 +1,11 @@
 SHELL = @SHELL@
 CC	= @CC@
-CFLAGS	= @CFLAGS@ -I. -DDEBUG -fPIC -fvisibility=hidden
+CFLAGS	= @CPPFLAGS@ @CFLAGS@ -I. -DDEBUG -fPIC -fvisibility=hidden
 OBJS	= triostr.o trio.o trionan.o
 TARGETLIB	= libtrio.a
 TARGETSHLIB	= $(TARGETLIB:.a=.so.2.0.0)
 TARGETINCS	= trio.h triop.h triodef.h trionan.h triostr.h
-LDFLAGS	= -L. -ltrio -lm
+LDFLAGS	= @LDFLAGS@ -L. -ltrio -lm
 AR	= ar
 RANLIB	= @RANLIB@
 ERASE	= rm -f
@@ -68,7 +68,7 @@ $(TARGETLIB): $(OBJS)
 	$(RANLIB) $(TARGETLIB)
 
 $(TARGETSHLIB): $(TARGETLIB)
-	$(CC) -lm -shared -Wl,-soname,$(patsubst %.so.2.0.0,%.so.2,$@) -Wl,--whole-archive,$< -Wl,--no-whole-archive -o $@
+	$(CC) -lm -shared -Wl,-soname,$(patsubst %.so.2.0.0,%.so.2,$@) -Wl,--whole-archive,$< -Wl,--no-whole-archive -o $@ $(LDFLAGS)
 
 doc::
 	(cd $(srcdir) && $(GENDOC) doc/trio.cfg)