diff --git a/Makefile b/Makefile
index c44bdc0..2aa40be 100644
--- a/Makefile
+++ b/Makefile
@@ -10,28 +10,7 @@ path_perf_test=${path_test}/perf
 
 perf_tests := $(shell find "$(path_perf_test)" -name 'perf-*.js')
 
-path_doc=./doc
-path_doc_output=${path_build}/doc
-path_doc_output_info=${path_doc_output}/easejs.info
-path_doc_output_plain=${path_doc_output}/manual.txt
-path_doc_output_html=${path_doc_output}/manual
-path_doc_output_html1=${path_doc_output}/manual.html
-path_doc_css=${path_doc}/manual.css
-path_doc_img=${path_doc}/img
-path_doc_css_ref=manual.css
-path_manual_texi=${path_doc}/manual.texi
-
-path_info_install := /usr/local/share/info
-
-src_js := index.js $(wildcard $(path_lib)/*.js)
-src_tests := index.js $(wildcard $(path_test)/test-*)
-doc_src := $(wildcard $(path_doc)/*.texi)
-doc_imgs := $(patsubst %.dia, %.png, $(wildcard $(path_doc_img)/*.dia))
-doc_imgs_txt := $(patsubst %.dia, %.png, $(wildcard $(path_doc_img)/*.txt))
-
-doc_replace := s/<\/body>/<script type="text\/javascript" \
-	src="highlight.pack.js"><\/script><script type="text\/javascript" \
-	src="interactive.js"><\/script><\/body>/
+path_doc := ./doc
 
 combine=${path_tools}/combine
 
@@ -45,10 +24,6 @@ all:     combine min doc
 # create build dir
 $(path_build):
 	mkdir -p "$(path_build)"
-$(path_doc_output):
-	mkdir -p "$(path_doc_output)"
-mkbuild: $(path_build)
-mkbuild-doc: $(path_doc_output)
 
 # combine all modules into easily redistributable ease.js file (intended for
 # browser)
@@ -60,6 +35,8 @@ $(path_build)/browser-test.html: $(path_combine_output_full)
 	cp "$(path_browser_test)" "$(path_build)"
 combine: $(path_combine_output) $(path_build)/browser-test.html
 
+doc:
+	$(MAKE) -C $(path_doc)
 
 test: default
 	$(MAKE) -C $(path_test)
@@ -69,76 +46,6 @@ perf: default $(perf_tests)
 perf-%.js: default
 	@node $@
 
-# generate texinfo documentation (twice to generate TOC), then remove the extra
-# files that were generated
-#
-# generates: pdf, info, HTML (multiple pages), HTML (single page)
-doc: | doc-pdf doc-info doc-plain doc-html
-
-# doc images
-doc/img/%.png: doc/img/%.dia
-	dia -e $@ -s 300x $<
-
-# doc pdf
-$(path_doc_output)/%.pdf: $(doc_src) $(doc_imgs) | mkbuild-doc doc-img
-	TEXINPUTS="$(path_doc):" \
-		pdftex -output-directory "${path_doc}" "${path_manual_texi}" && \
-		TEXINPUTS="$(path_doc):" \
-		pdftex -output-directory "${path_doc}" "${path_manual_texi}"
-	mv -f "${path_doc}"/*.pdf "${path_doc_output}"
-	cd "$(path_doc)" && rm -f $(shell cat "$(path_doc)/.gitignore")
-
-# doc info
-$(path_doc_output_info): $(doc_src) $(doc_imgs_txt) | mkbuild-doc
-	makeinfo -I "$(path_doc)" -o $@ "$(path_manual_texi)";
-
-# doc plain text
-$(path_doc_output_plain): $(doc_imgs_txt) | mkbuild-doc
-	makeinfo --plain -I "$(path_doc)" "${path_manual_texi}" > $@
-
-# doc html (multiple pages)
-$(path_doc_output_html)/index.html: $(doc_src) $(path_doc_css) \
-| $(path_doc_output_html)/img $(path_doc_output_html)/interactive.js \
-$(path_doc_output_html)/highlight.pack.js \
-$(path_doc_output_html)/$(path_doc_css_ref) mkbuild-doc doc-img
-	makeinfo --html --css-ref="$(path_doc_css_ref)" \
-		-I "$(path_doc)" -o "${path_doc_output_html}" "${path_manual_texi}"
-	sed -i '$(doc_replace)' $(path_doc_output_html)/*.htm?
-
-# doc html (single page)
-$(path_doc_output_html1): $(doc_src) $(path_doc_css) \
-| $(path_doc_output)/img $(path_doc_output)/interactive.js \
-$(path_doc_output)/highlight.pack.js mkbuild-doc doc-img
-	makeinfo --no-split --html --css-include="${path_doc_css}" \
-		-I "$(path_doc)" -o - "${path_manual_texi}" \
-		| sed '$(doc_replace)' \
-			> "$(path_doc_output_html1)"
-
-# doc images (in build dir)
-$(path_doc_output)/img: $(doc_imgs) | mkbuild-doc doc-img
-	mkdir -p $@
-	cp "$(path_doc_img)"/*.png $@
-$(path_doc_output_html)/img: $(path_doc_output)/img
-	mkdir -p $(path_doc_output_html)
-	ln -s ../img $@
-
-# interactive html doc (js)
-$(path_doc_output_html)/%.js: $(path_doc)/%.js
-	cp $< $@
-$(path_doc_output)/%.js: $(path_doc)/%.js
-	cp $< $@
-
-# doc css
-$(path_doc_output_html)/%.css: $(path_doc)/%.css
-	cp $< $@
-
-
-doc-img: $(doc_imgs)
-doc-pdf: $(path_doc_output)/manual.pdf
-doc-info: $(path_doc_output_info)
-doc-plain: $(path_doc_output_plain)
-doc-html: $(path_doc_output_html)/index.html $(path_doc_output_html1)
-
 min: build/ease.min.js build/ease-full.min.js
 build/%.min.js: build/%.js
 	cat $(path_tools)/license.tpl > $@
@@ -153,6 +60,6 @@ uninstall:
 
 # clean up build dir
 clean:
+	$(MAKE) -C $(path_doc) clean
 	rm -rf "${path_build}"
-	rm -rf $(path_doc_img)/*.png
 
diff --git a/doc/Makefile b/doc/Makefile
new file mode 100644
index 0000000..6b03931
--- /dev/null
+++ b/doc/Makefile
@@ -0,0 +1,109 @@
+# documentation
+
+path_doc=.
+path_build=../build
+path_lib=../lib
+path_doc_output=${path_build}/doc
+path_doc_output_info=${path_doc_output}/easejs.info
+path_doc_output_plain=${path_doc_output}/manual.txt
+path_doc_output_html=${path_doc_output}/manual
+path_doc_output_html1=${path_doc_output}/manual.html
+path_doc_css=${path_doc}/manual.css
+path_doc_img=${path_doc}/img
+path_doc_css_ref=manual.css
+path_manual_texi=${path_doc}/manual.texi
+
+path_info_install := /usr/local/share/info
+
+src_js := index.js $(wildcard $(path_lib)/*.js)
+src_tests := index.js $(wildcard $(path_test)/test-*)
+doc_src := $(wildcard $(path_doc)/*.texi)
+doc_imgs := $(patsubst %.dia, %.png, $(wildcard $(path_doc_img)/*.dia))
+doc_imgs_txt := $(patsubst %.dia, %.png, $(wildcard $(path_doc_img)/*.txt))
+
+doc_replace := s/<\/body>/<script type="text\/javascript" \
+	src="highlight.pack.js"><\/script><script type="text\/javascript" \
+	src="interactive.js"><\/script><\/body>/
+
+.PHONY: doc mkbuild-doc doc-img doc-pdf doc-info doc-plain doc-html
+
+# generate texinfo documentation (twice to generate TOC), then remove the extra
+# files that were generated
+#
+# generates: pdf, info, HTML (multiple pages), HTML (single page)
+default: doc-pdf doc-info doc-plain doc-html
+
+mkbuild-doc: $(path_doc_output)
+
+$(path_doc_output):
+	[ -d $(path_doc_output) ] || mkdir -p "$(path_doc_output)"
+mkbuild: $(path_build)
+
+# doc images
+$(path_doc)/img/%.png: $(path_doc)/img/%.dia
+	dia -e $@ -s 300x $<
+
+# doc pdf
+$(path_doc_output)/%.pdf: $(doc_src) $(doc_imgs) | mkbuild-doc doc-img
+	TEXINPUTS="$(path_doc):" \
+		pdftex -output-directory "${path_doc}" "${path_manual_texi}" && \
+		TEXINPUTS="$(path_doc):" \
+		pdftex -output-directory "${path_doc}" "${path_manual_texi}"
+	mv -f "${path_doc}"/*.pdf "${path_doc_output}"
+	cd "$(path_doc)" && rm -f $(shell cat "$(path_doc)/.gitignore")
+
+# doc info
+$(path_doc_output_info): $(doc_src) $(doc_imgs_txt) | mkbuild-doc
+	makeinfo -I "$(path_doc)" -o $@ "$(path_manual_texi)";
+
+# doc plain text
+$(path_doc_output_plain): $(doc_imgs_txt) | mkbuild-doc
+	makeinfo --plain -I "$(path_doc)" "${path_manual_texi}" > $@
+
+# doc html (multiple pages)
+$(path_doc_output_html)/index.html: $(doc_src) $(path_doc_css) \
+| $(path_doc_output_html)/img $(path_doc_output_html)/interactive.js \
+$(path_doc_output_html)/highlight.pack.js \
+$(path_doc_output_html)/$(path_doc_css_ref) mkbuild-doc doc-img
+	makeinfo --html --css-ref="$(path_doc_css_ref)" \
+		-I "$(path_doc)" -o "${path_doc_output_html}" "${path_manual_texi}"
+	sed -i '$(doc_replace)' $(path_doc_output_html)/*.htm?
+
+# doc html (single page)
+$(path_doc_output_html1): $(doc_src) $(path_doc_css) \
+| $(path_doc_output)/img $(path_doc_output)/interactive.js \
+$(path_doc_output)/highlight.pack.js mkbuild-doc doc-img
+	makeinfo --no-split --html --css-include="${path_doc_css}" \
+		-I "$(path_doc)" -o - "${path_manual_texi}" \
+		| sed '$(doc_replace)' \
+			> "$(path_doc_output_html1)"
+
+# doc images (in build dir)
+$(path_doc_output)/img: $(doc_imgs) | mkbuild-doc doc-img
+	[ -d "$@" ] || mkdir -p $@
+	cp "$(path_doc_img)"/*.png $@
+$(path_doc_output_html)/img: $(path_doc_output)/img
+	mkdir -p $(path_doc_output_html)
+	ln -s ../img $@
+
+# interactive html doc (js)
+$(path_doc_output_html)/%.js: $(path_doc)/%.js
+	cp $< $@
+$(path_doc_output)/%.js: $(path_doc)/%.js
+	cp $< $@
+
+# doc css
+$(path_doc_output_html)/%.css: $(path_doc)/%.css
+	cp $< $@
+
+
+doc-img: $(doc_imgs)
+doc-pdf: $(path_doc_output)/manual.pdf
+doc-info: $(path_doc_output_info)
+doc-plain: $(path_doc_output_plain)
+doc-html: $(path_doc_output_html)/index.html $(path_doc_output_html1)
+
+clean:
+	rm -rf $(path_doc_output)
+	rm -rf $(path_doc_img)/*.png
+