diff --git a/AstroAtmosphere/refractivityModels.py b/AstroAtmosphere/refractivityModels.py
index 1c58f2c..d4476c2 100644
--- a/AstroAtmosphere/refractivityModels.py
+++ b/AstroAtmosphere/refractivityModels.py
@@ -193,7 +193,12 @@ def slalib(l, T=288.15, p=101325, H=0, h=0, lat=-24, tlr=0.0065, eps=1e-10):
 		Returns:
 		n - Refractive index of atmospheric air at the given conditions
 	'''
-	from pyslalib import slalib
+	try:
+	    from pyslalib import slalib
+	except ImportError as e:
+	    print('pySLALIB package not found! Try installing it first.\nReturning n=1.')
+	    return 1
+	
 	zObs = np.deg2rad(45.06563)
 	p = p/100
 	R = []
diff --git a/setup.py b/setup.py
index 092b891..3edf9d6 100644
--- a/setup.py
+++ b/setup.py
@@ -21,14 +21,14 @@ def setup_package():
     # write_version_py()
 
     setup(name='AstroAtmosphere',
-          version='0.1.1',
+          version='0.1.2',
           description='Collection of equations for refractive index, refraction and dispersion calculations of atmospheric air.',
           long_description=__readme__,
           long_description_content_type='text/markdown',
           author='Joost van den Born',
           author_email='born@astron.nl',
           url='https://gitlab.astro-wise.org/micado/atmosphericmodel',
-          download_url='https://gitlab.astro-wise.org/micado/atmosphericmodel/-/archive/v_01/atmosphericmodel-v_01.tar.gz',
+          download_url='https://gitlab.astro-wise.org/micado/atmosphericmodel/-/archive/v_012/atmosphericmodel-v_012.tar.gz',
           license='GNU General Public License v3',
           data_files = [('',['LICENSE.txt'])],
           package_dir={'AstroAtmosphere': 'AstroAtmosphere'},
@@ -37,9 +37,8 @@ def setup_package():
           packages=['AstroAtmosphere'],
           keywords=['REFRACTION','REFRACTIVITY','ATMOSPHERE','DISPERSION','CIDDOR'],
           install_requires=['numpy',
-                            'scipy',
-                            'pyslalib>=1.0.4'
-                            ],
+                            'scipy'],
+          extras_require={'slalib':['pyslalib>=1.0.4']},
           classifiers=['Programming Language :: Python :: 3',
                        'Operating System :: OS Independent',
                        'Intended Audience :: Science/Research',