diff --git a/.github/workflows/test.yaml b/.github/workflows/test.yaml
index c92b15b..4337d0f 100644
--- a/.github/workflows/test.yaml
+++ b/.github/workflows/test.yaml
@@ -26,7 +26,7 @@ jobs:
           pip install -e ./flex
       - name: Test with pytest  
         run: |  
-          coverage run -m pytest  -v -s  
+          coverage run -m pytest -v -s  
       - name: Upload coverage to Coveralls
         run: coveralls --service=github
         env:
diff --git a/pytest.ini b/pytest.ini
new file mode 100644
index 0000000..08ba66f
--- /dev/null
+++ b/pytest.ini
@@ -0,0 +1,2 @@
+[pytest]
+addopts = --ignore=flex
diff --git a/src/discmodel/discmodel.py b/src/discmodel/discmodel.py
index ea4c34c..7179097 100644
--- a/src/discmodel/discmodel.py
+++ b/src/discmodel/discmodel.py
@@ -139,26 +139,26 @@ def rotate_disc(self,xrotation=0.,yrotation=0.,zrotation=0.,euler=False):
         # do the transformation in position
         tmp = np.dot(np.array([x,y,z]).T,Rmatrix)
         
-        try:
-            xout = tmp[:,0]
-            yout = tmp[:,1]
-            zout = tmp[:,2]
-        except:
-            xout = tmp[0]
-            yout = tmp[1]
-            zout = tmp[2]
+        #try:
+        xout = tmp[:,0]
+        yout = tmp[:,1]
+        zout = tmp[:,2]
+        #except:
+        #    xout = tmp[0]
+        #    yout = tmp[1]
+        #    zout = tmp[2]
 
         # and in velocity
         tmpv = np.dot(np.array([u,v,w]).T,Rmatrix)
 
-        try:
-            uout = tmpv[:,0]
-            vout = tmpv[:,1]
-            wout = tmpv[:,2]
-        except:
-            uout = tmpv[0]
-            vout = tmpv[1]
-            wout = tmpv[2]        
+        #try:
+        uout = tmpv[:,0]
+        vout = tmpv[:,1]
+        wout = tmpv[:,2]
+        #except:
+        #    uout = tmpv[0]
+        #    vout = tmpv[1]
+        #    wout = tmpv[2]        
 
         self.x = xout
         self.y = yout
diff --git a/src/discmodel/optional_imports.py b/src/discmodel/optional_imports.py
index a043b9f..2c5078e 100644
--- a/src/discmodel/optional_imports.py
+++ b/src/discmodel/optional_imports.py
@@ -10,7 +10,7 @@ def _check_lintsampler():
 def _check_flex():
     try:
         import importlib
-        importlib.import_module("lintsampler")
+        importlib.import_module("flex")
         return True
     except ImportError:
         return False
diff --git a/tests/test_discmodel.py b/tests/test_discmodel.py
index 57e12a9..e5899e3 100644
--- a/tests/test_discmodel.py
+++ b/tests/test_discmodel.py
@@ -122,6 +122,9 @@ def test_discmodel_expansion():
     nbins = 50
 
     disc = discmodel.DiscGalaxy(N=N, a=a, M=M, vcirc=vcirc, rmax=rmax)
+
+    # try to compute expansion before image - should raise error
+
     disc.generate_image(rmax,nbins,noiselevel=noiselevel)
 
     # add some noise
@@ -132,9 +135,12 @@ def test_discmodel_expansion():
     # compute the expansion
     E1 = disc.make_expansion(mmax=4,nmax=4,rscl=1.0,xmax=rmax,noisy=False)
 
+    # compute a noisy expansion
+    E2 = disc.make_expansion(mmax=4,nmax=4,rscl=1.0,xmax=rmax,noisy=True)
+    assert E2 is not None
     # compute the expansion from the particles
-    E2 = disc.make_particle_expansion(mmax=4,nmax=4,rscl=1.0)
-
+    E3 = disc.make_particle_expansion(mmax=4,nmax=4,rscl=1.0)
+    assert E3 is not None
     # compute A1
     a1 = disc.compute_a1(E1)