diff --git a/Makefile b/Makefile
index 15aa8cd4..93d04af9 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,19 @@
+bs := $(shell command -v bikeshed 2> /dev/null)
+
 all : index.html
 
 index.html : index.bs
+ifdef bs
 	bikeshed spec index.bs
+else
+	@echo Cannot find a local version of Bikeshed. To install it, visit:
+	@echo
+	@echo https://github.com/tabatkins/bikeshed/blob/master/docs/install.md
+	@echo
+	@echo Trying to build the spec using the online API at: https://api.csswg.org/bikeshed/
+	@echo This will fail if you are not connected to the network.
+	curl https://api.csswg.org/bikeshed/ -F file=@index.bs > index.html
+endif
 
 clean :
 	rm -f index.html