diff --git a/README.md b/README.md
index 5a12c2b..c8869e7 100644
--- a/README.md
+++ b/README.md
@@ -13,6 +13,7 @@ CartoDB Spatial Analysis extension for PostgreSQL.
 ## Requirements
 
 * pip, virtualenv, PostgreSQL
+* python-scipy system package
 
 # Working Process
 
diff --git a/src/py/Makefile b/src/py/Makefile
index 27d1446..16be269 100644
--- a/src/py/Makefile
+++ b/src/py/Makefile
@@ -1,8 +1,8 @@
 # Install the package locally for development
 install:
-	virtualenv dev
-	./dev/bin/pip install ./crankshaft --upgrade
-	./dev/bin/pip install nose
+	virtualenv --system-site-packages dev
+	./dev/bin/pip install -I ./crankshaft
+	./dev/bin/pip install -I nose
 
 # Test develpment install
 testinstalled:
diff --git a/src/py/crankshaft/setup.py b/src/py/crankshaft/setup.py
index c0f8c50..aaa76a6 100644
--- a/src/py/crankshaft/setup.py
+++ b/src/py/crankshaft/setup.py
@@ -40,9 +40,9 @@ setup(
 
     # The choice of component versions is dictated by what's
     # provisioned in the production servers.
-    install_requires=['pysal==1.11.0','numpy==1.6.1','scipy==0.17.0'],
+    install_requires=['pysal==1.9.1'],
 
-    requires=['pysal', 'numpy'],
+    requires=['pysal', 'numpy' ],
 
     test_suite='test'
 )