diff --git a/Makefile b/Makefile
index b4a49f8..e799278 100644
--- a/Makefile
+++ b/Makefile
@@ -7,12 +7,12 @@ LIBDIR=$(DESTDIR)/usr/lib
 INSTALL=install
 
 # You may need to change the -I arguments depending on your system
-CFLAGS=-O3 -I/usr/include/tcl8.3/ -I/usr/include/tcl
+CFLAGS+=-I/usr/include/tcl
 
 all:	libfilecmp.so.0.0
 
 libfilecmp.so.0.0: filecmp.c
-	$(CC) $(CFLAGS) -shared -o $@ filecmp.c
+	$(CC) $(CFLAGS) $(LDFLAGS) -Wl,-soname,libfilecmp.so.0 -shared -fPIC -o $@ filecmp.c
 
 install: dirdiff libfilecmp.so.0.0
 	$(INSTALL) -c dirdiff $(BINDIR)