diff --git a/makefile.shared b/makefile.shared
index eea79e5..e4fc103 100644
--- a/makefile.shared
+++ b/makefile.shared
@@ -47,8 +47,8 @@ $(LIBNAME): $(OBJECTS)
 
 install: .common_install
 	sed -e 's,^prefix=.*,prefix=$(PREFIX),' -e 's,^Version:.*,Version: $(VERSION),' libtomcrypt.pc.in > libtomcrypt.pc
-	install -d $(LIBPATH)/pkgconfig
-	install -m 644 libtomcrypt.pc $(LIBPATH)/pkgconfig/
+	install -d $(DESTDIR)/$(LIBPATH)/pkgconfig
+	install -m 644 libtomcrypt.pc $(DESTDIR)/$(LIBPATH)/pkgconfig/
 
 install_bins: .common_install_bins
 
diff --git a/makefile.unix b/makefile.unix
index 88f88a0..d3ccc72 100644
--- a/makefile.unix
+++ b/makefile.unix
@@ -25,10 +25,10 @@
 #The following can be overridden from command line e.g. "make -f makefile.unix CC=gcc ARFLAGS=rcs"
 DESTDIR   =
 PREFIX    = /usr/local
-LIBPATH   = $(DESTDIR)$(PREFIX)/lib
-INCPATH   = $(DESTDIR)$(PREFIX)/include
-DATAPATH  = $(DESTDIR)$(PREFIX)/share/doc/libtomcrypt/pdf
-BINPATH   = $(DESTDIR)$(PREFIX)/bin
+LIBPATH   = $(PREFIX)/lib
+INCPATH   = $(PREFIX)/include
+DATAPATH  = $(PREFIX)/share/doc/libtomcrypt/pdf
+BINPATH   = $(PREFIX)/bin
 CC        = cc
 AR        = ar
 ARFLAGS   = r
@@ -272,17 +272,17 @@ clean:
 
 #Install the library + headers
 install: $(LIBMAIN_S) $(HEADERS)
-	@mkdir -p $(INCPATH) $(LIBPATH)/pkgconfig
-	@cp $(LIBMAIN_S) $(LIBPATH)/
-	@cp $(HEADERS) $(INCPATH)/
-	@sed -e 's,^prefix=.*,prefix=$(PREFIX),' -e 's,^Version:.*,Version: $(VERSION),' libtomcrypt.pc.in > $(LIBPATH)/pkgconfig/libtomcrypt.pc
+	@mkdir -p $(DESTDIR)/$(INCPATH) $(DESTDIR)/$(LIBPATH)/pkgconfig
+	@cp $(LIBMAIN_S) $(DESTDIR)/$(LIBPATH)/
+	@cp $(HEADERS) $(DESTDIR)/$(INCPATH)/
+	@sed -e 's,^prefix=.*,prefix=$(PREFIX),' -e 's,^Version:.*,Version: $(VERSION),' libtomcrypt.pc.in > $(DESTDIR)/$(LIBPATH)/pkgconfig/libtomcrypt.pc
 
 #Install useful tools
 install_bins: hashsum
-	@mkdir -p $(BINPATH)
-	@cp hashsum $(BINPATH)/
+	@mkdir -p $(DESTDIR)/$(BINPATH)
+	@cp hashsum $(DESTDIR)/$(BINPATH)/
 
 #Install documentation
 install_docs: doc/crypt.pdf
-	@mkdir -p $(DATAPATH)
-	@cp doc/crypt.pdf $(DATAPATH)/
+	@mkdir -p $(DESTDIR)/$(DATAPATH)
+	@cp doc/crypt.pdf $(DESTDIR)/$(DATAPATH)/
diff --git a/makefile_include.mk b/makefile_include.mk
index daf7657..6d13009 100644
--- a/makefile_include.mk
+++ b/makefile_include.mk
@@ -132,10 +132,10 @@ TIMINGS=demos/timing.o
 #BINPATH  The directory to install the binaries provided.
 DESTDIR  ?=
 PREFIX   ?= /usr/local
-LIBPATH  ?= $(DESTDIR)$(PREFIX)/lib
-INCPATH  ?= $(DESTDIR)$(PREFIX)/include
-DATAPATH ?= $(DESTDIR)$(PREFIX)/share/doc/libtomcrypt/pdf
-BINPATH  ?= $(DESTDIR)$(PREFIX)/bin
+LIBPATH  ?= $(PREFIX)/lib
+INCPATH  ?= $(PREFIX)/include
+DATAPATH ?= $(PREFIX)/share/doc/libtomcrypt/pdf
+BINPATH  ?= $(PREFIX)/bin
 
 #Who do we install as?
 ifdef INSTALL_USER
@@ -362,18 +362,18 @@ install_all: install install_bins install_docs install_test
 INSTALL_OPTS ?= -m 644
 
 .common_install: $(LIBNAME)
-	install -d $(INCPATH)
-	install -d $(LIBPATH)
-	$(INSTALL_CMD) $(INSTALL_OPTS) $(LIBNAME) $(LIBPATH)/$(LIBNAME)
-	install -m 644 $(HEADERS) $(INCPATH)
+	install -d $(DESTDIR)/$(INCPATH)
+	install -d $(DESTDIR)/$(LIBPATH)
+	$(INSTALL_CMD) $(INSTALL_OPTS) $(LIBNAME) $(DESTDIR)/$(LIBPATH)/$(LIBNAME)
+	install -m 644 $(HEADERS) $(DESTDIR)/$(INCPATH)
 
 .common_install_bins: $(USEFUL_DEMOS)
 	install -d $(BINPATH)
-	$(INSTALL_CMD) -m 775 $(USEFUL_DEMOS) $(BINPATH)
+	$(INSTALL_CMD) -m 775 $(USEFUL_DEMOS) $(DESTDIR)/$(BINPATH)
 
 install_docs: doc/crypt.pdf
 	install -d $(DATAPATH)
-	install -m 644 doc/crypt.pdf $(DATAPATH)
+	install -m 644 doc/crypt.pdf $(DESTDIR)/$(DATAPATH)
 
 install_hooks:
 	for s in `ls hooks/`; do ln -s ../../hooks/$$s .git/hooks/$$s; done