diff --git a/Makefile b/Makefile
index 4666695..bac58a5 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,8 @@
+INSTALL = install -D
+
 export DESTDIR ?= /usr/local
+export INSTALL_PROGRAM = $(INSTALL)
+export INSTALL_DATA = $(INSTALL) -m 644
 
 dirs = src doc conkeror
 install-dirs = $(addprefix install-,$(dirs))
diff --git a/conkeror/Makefile b/conkeror/Makefile
index 25ffd14..5d21926 100644
--- a/conkeror/Makefile
+++ b/conkeror/Makefile
@@ -4,7 +4,7 @@ DESTDIR ?= /usr/local
 
 all:
 install: markam.js
-	install -Dm 655 markam.js \
+	$(INSTALL_DATA) markam.js \
 		"$(DESTDIR)/share/conkeror/modules/markam.js"
 
 uninstall:
diff --git a/doc/Makefile b/doc/Makefile
index dbea1f8..36b33c4 100644
--- a/doc/Makefile
+++ b/doc/Makefile
@@ -1,4 +1,7 @@
 DESTDIR ?= /usr/local
+INSTALL_INFO = install-info
+TEXI2PDF = texi2pdf
+DVIPS = dvips
 
 .PHONY: all html dvi pdf ps install uninstall install-dvi install-pdf \
 		install-ps
@@ -6,12 +9,12 @@ DESTDIR ?= /usr/local
 all: markam.info
 
 install: markam.info
-	install -Dm 655 markam.info "$(DESTDIR)/share/info/markam.info"
-	install-info --dir-file="$(DESTDIR)/share/info/dir" \
+	$(INSTALL_DATA) markam.info "$(DESTDIR)/share/info/markam.info"
+	$(INSTALL_INFO) --dir-file="$(DESTDIR)/share/info/dir" \
 		"$(DESTDIR)/share/info/markam.info"
 
 uninstall:
-	install-info --dir-file="$(DESTDIR)/share/info/dir" \
+	$(INSTALL_INFO) --dir-file="$(DESTDIR)/share/info/dir" \
 		--delete "$(DESTDIR)/share/info/markam.info"
 	rm -f "$(DESTDIR)/share/info/markam.info"
 	rm -f "$(DESTDIR)/share/doc/markam/dvi/markam.dvi"
@@ -20,31 +23,31 @@ uninstall:
 	rm -rf "$(DESTDIR)/share/doc/markam/html/"
 
 install-dvi: markam.dvi
-	install -Dm 655 markam.dvi \
+	$(INSTALL_DATA) markam.dvi \
 		"$(DESTDIR)/share/doc/markam/dvi/markam.dvi"
 
 install-pdf: markam.pdf
-	install -Dm 655 markam.pdf \
+	$(INSTALL_DATA) markam.pdf \
 		"$(DESTDIR)/share/doc/markam/pdf/markam.pdf"
 
 install-ps: markam.ps
-	install -Dm 655 markam.ps \
+	$(INSTALL_DATA) markam.ps \
 		"$(DESTDIR)/share/doc/markam/ps/markam.ps"
 
 markam.info: markam.texi
 
 html: markam.texi
-	makeinfo --html markam.texi -o html
+	$(MAKEINFO) --html markam.texi -o html
 
 dvi: markam.dvi
 pdf: markam.pdf
 ps: markam.ps
 
 markam.dvi: markam.texi
-	texi2dvi markam.texi
+	$(TEXI2DVI) markam.texi
 
 markam.pdf: markam.texi
-	texi2pdf markam.texi
+	$(TEXI2PDF) markam.texi
 
 markam.ps: markam.dvi
-	dvips markam.dvi
+	$(DVIPS) markam.dvi
diff --git a/src/Makefile b/src/Makefile
index 961ad1b..a7d2415 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -1,4 +1,5 @@
 DESTDIR ?= /usr/local
+CSC = csc
 
 binaries = markam markam-convert
 install-binaries = $(addprefix install-,$(binaries))
@@ -12,16 +13,16 @@ install: $(install-binaries)
 uninstall: $(uninstall-binaries)
 
 markam: markam.scm $(objects)
-	csc $^ -o $@
+	$(CSC) $^ -o $@
 
 markam-convert: markam-convert.scm $(objects)
-	csc $^ -o $@
+	$(CSC) $^ -o $@
 
 $(install-binaries): install-%: %
-	install -Dm 755 $* "$(DESTDIR)/bin/$*"
+	$(INSTALL_PROGRAM) $* "$(DESTDIR)/bin/$*"
 
 $(uninstall-binaries): uninstall-%:
 	rm -f "$(DESTDIR)/bin/$*"
 
 $(objects): %.o: %.scm
-	csc -c $^
+	$(CSC) -c $^