diff --git a/Makefile b/Makefile
index 54b82ea1b070975b2c049071b534da0a8e05eaa5..031ec13d0b01e8957312fa9f0405e11e928caed9 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 all: html
 
-build/%.ipynb: %.md build/md2ipynb.py $(wildcard gluonbook/*)
+build/%.ipynb: %.md build/env.yml build/md2ipynb.py $(wildcard gluonbook/*)
 	@mkdir -p $(@D)
 	cd $(@D); python ../md2ipynb.py ../../$< ../../$@