diff --git a/Makefile b/Makefile
index 9a6c54a..0fef914 100644
--- a/Makefile
+++ b/Makefile
@@ -27,7 +27,7 @@ docs:
 
 install-deps:
 	$(PIP) install --upgrade pip
-	$(PIP) install --upgrade -i https://pypi.gurobi.com gurobipy
+	$(PIP) install --upgrade -i https://pypi.gurobi.com 'gurobipy>=9.1,<9.2'
 	$(PIP) install --upgrade xpress
 	$(PIP) install --upgrade -r requirements.txt