diff --git a/var/spack/repos/builtin/packages/py-astropy/package.py b/var/spack/repos/builtin/packages/py-astropy/package.py
index bac794e551..e3776caf70 100644
--- a/var/spack/repos/builtin/packages/py-astropy/package.py
+++ b/var/spack/repos/builtin/packages/py-astropy/package.py
@@ -37,8 +37,8 @@ class PyAstropy(Package):
     version('1.1.post1', 'b52919f657a37d45cc45f5cb0f58c44d')
 
     # Required dependencies
-    extends('python@2.6.5:2.7,3.3:')
-    depends_on('py-numpy@1.6.0:')
+    extends('python')
+    depends_on('py-numpy')
 
     # Optional dependencies
     depends_on('cfitsio')
@@ -60,5 +60,4 @@ class PyAstropy(Package):
     def install(self, spec, prefix):
         python('setup.py', 'build', '--use-system-cfitsio',
                '--use-system-expat')
-        python('setup.py', 'install', '--single-version-externally-managed',
-               '--root=/', '--prefix={0}'.format(prefix))
+        python('setup.py', 'install', '--prefix={0}'.format(prefix))
diff --git a/var/spack/repos/builtin/packages/py-h5py/package.py b/var/spack/repos/builtin/packages/py-h5py/package.py
index 1b8675ecf2..1379513197 100644
--- a/var/spack/repos/builtin/packages/py-h5py/package.py
+++ b/var/spack/repos/builtin/packages/py-h5py/package.py
@@ -54,5 +54,4 @@ def install(self, spec, prefix):
             env['CC'] = spec['mpi'].mpicc
             python('setup.py', 'configure', '--mpi')
 
-        python('setup.py', 'install', '--single-version-externally-managed',
-               '--root=/', '--prefix={0}'.format(prefix))
+        python('setup.py', 'install', '--prefix={0}'.format(prefix))
diff --git a/var/spack/repos/builtin/packages/py-iminuit/package.py b/var/spack/repos/builtin/packages/py-iminuit/package.py
index 557cf19c19..ffc5a5bd14 100644
--- a/var/spack/repos/builtin/packages/py-iminuit/package.py
+++ b/var/spack/repos/builtin/packages/py-iminuit/package.py
@@ -34,7 +34,7 @@ class PyIminuit(Package):
     version('1.2', '4701ec472cae42015e26251703e6e984')
 
     # Required dependencies
-    extends('python@2.7:2.8,3.4:')
+    extends('python')
     depends_on('py-setuptools')
 
     # Optional dependencies
@@ -42,5 +42,4 @@ class PyIminuit(Package):
     depends_on('py-matplotlib')
 
     def install(self, spec, prefix):
-        python('setup.py', 'install', '--single-version-externally-managed',
-               '--root=/', '--prefix={0}'.format(prefix))
+        python('setup.py', 'install', '--prefix={0}'.format(prefix))
diff --git a/var/spack/repos/builtin/packages/py-nestle/package.py b/var/spack/repos/builtin/packages/py-nestle/package.py
index 38fa0561db..16506e3eca 100644
--- a/var/spack/repos/builtin/packages/py-nestle/package.py
+++ b/var/spack/repos/builtin/packages/py-nestle/package.py
@@ -35,7 +35,7 @@ class PyNestle(Package):
 
     # Required dependencies
     extends('python')
-    depends_on('py-numpy@1.6:')
+    depends_on('py-numpy')
 
     # Optional dependencies
     depends_on('py-scipy')
diff --git a/var/spack/repos/builtin/packages/py-sncosmo/package.py b/var/spack/repos/builtin/packages/py-sncosmo/package.py
index 58c4625a4f..8976413ab9 100644
--- a/var/spack/repos/builtin/packages/py-sncosmo/package.py
+++ b/var/spack/repos/builtin/packages/py-sncosmo/package.py
@@ -36,7 +36,7 @@ class PySncosmo(Package):
 
     # Required dependencies
     # py-sncosmo binaries are duplicates of those from py-astropy
-    extends('python@2.6:2.7,3.3:', ignore=r'bin/*')
+    extends('python', ignore=r'bin/*')
     depends_on('py-numpy')
     depends_on('py-scipy')
     depends_on('py-astropy')
@@ -48,5 +48,4 @@ class PySncosmo(Package):
     depends_on('py-nestle')
 
     def install(self, spec, prefix):
-        python('setup.py', 'install', '--single-version-externally-managed',
-               '--root=/', '--prefix={0}'.format(prefix))
+        python('setup.py', 'install', '--prefix={0}'.format(prefix))