diff --git a/Makefile b/Makefile
index 4e870a452..b656d5d9b 100644
--- a/Makefile
+++ b/Makefile
@@ -4,6 +4,7 @@ outdoc_files = $(addprefix out/,$(doc_sources:.md=.html))
 docassets = $(addprefix out/,$(wildcard doc/assets/*))
 
 VERSION = $(shell node -e "console.log( require('./src/package.json').version )") 
+UNAME := $(shell uname -s)
 
 docs: $(outdoc_files) $(docassets)
 
@@ -14,7 +15,11 @@ out/doc/assets/%: doc/assets/%
 out/doc/%.html: doc/%.md
 	mkdir -p $(@D)
 	node tools/doc/generate.js --format=html --template=doc/template.html $< > $@
-	cat $@ | sed 's/__VERSION__/${VERSION}/' > $@
+ifeq ($(UNAME),Darwin)
+	sed -i '' 's/__VERSION__/${VERSION}/' $@
+else
+	sed -i 's/__VERSION__/${VERSION}/' $@
+endif
 
 clean:
 	rm -rf out/