diff --git a/Makefile b/Makefile
index 103a4fa..d791ff5 100644
--- a/Makefile
+++ b/Makefile
@@ -3,21 +3,27 @@ CSS    = style.css
 PAGES  = index.html
 IMAGES = mlem.gif icon.png
 
-all: $(patsubst %,_build/%,$(FONTS) $(CSS) $(PAGES) $(IMAGES))
+BUILDDIR ?= _build
+TMPDIR   ?= _tmp
 
-_build/%: %
+
+all: build
+
+build: $(patsubst %,$(BUILDDIR)/%,$(FONTS) $(CSS) $(PAGES) $(IMAGES))
+
+$(BUILDDIR)/%: %
 	@echo $*
 	@mkdir -p $(dir $@)
 	@cp $< $@
 
-_build/%.gif: %_bg.gif
+$(BUILDDIR)/%.gif: %_bg.gif
 	@echo $*.gif
-	@mkdir -p $(dir _build/%* _tmp/%*)
-	@gifsicle -U $*_bg.gif -o _tmp/$*_bg_u.gif
-	@convert -transparent '#ff9bc7' _tmp/$*_bg_u.gif _tmp/$*_t.gif
-	@gifsicle --disposal=previous _tmp/$*_t.gif -o _build/$*.gif
+	@mkdir -p $(dir $(BUILDDIR)/%* $(TMPDIR)/%*)
+	@gifsicle -U $*_bg.gif -o $(TMPDIR)/$*_bg_u.gif
+	@convert -transparent '#ff9bc7' $(TMPDIR)/$*_bg_u.gif $(TMPDIR)/$*_t.gif
+	@gifsicle --disposal=previous $(TMPDIR)/$*_t.gif -o $(BUILDDIR)/$*.gif
 
 clean:
-	$(RM) -r _tmp _build
+	$(RM) -r $(TMPDIR) $(BUILDDIR)
 
-.PHONY: clean
+.PHONY: clean all build