--- Makefile.in
+++ Makefile.in
@@ -127,8 +127,8 @@
 prefix = $(INSTALL_ROOT)@prefix@
 exec_prefix = $(INSTALL_ROOT)@exec_prefix@
 
-libdir = @libdir@
-mandir = @mandir@
+libdir = $(INSTALL_ROOT)@libdir@
+mandir = $(INSTALL_ROOT)@mandir@
 
 DESTDIR =
 
