diff --git a/Makefile b/Makefile
index 2299f38..4de9093 100644
--- a/Makefile
+++ b/Makefile
@@ -11,12 +11,13 @@ lint:
 test: all
 	py.test
 
+REPO = jeffkimbrel/qSIP2
+HASH = fee266bb14836f7a6c45ef9ef11d451999936a3a
 install: all
 	pip install .
 	conda install --yes r-devtools r-svglite r-gt rpy2 -c r
 	Rscript -e 'install.packages("S7", repos="https://cloud.r-project.org")'
-	# TODO: don't just install HEAD
-	Rscript -e 'devtools::install_github("jeffkimbrel/qSIP2")'
+	Rscript -e 'devtools::install_github("$(REPO)", ref="$(HASH)")'
 
 dev: all
 	pip install -e .