diff --git a/.travis.yml b/.travis.yml
index d212b5723c..5110aac88e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -79,7 +79,7 @@ install:
     - source activate test
 
     # CORE DEPENDENCIES
-    - if [[ $SETUP_CMD != egg_info ]]; then $CONDA_INSTALL numpy=$NUMPY_VERSION pytest pip Cython; fi
+    - if [[ $SETUP_CMD != egg_info ]]; then $CONDA_INSTALL numpy=$NUMPY_VERSION pytest pip Cython jinja2; fi
     - if [[ $SETUP_CMD != egg_info ]]; then $PIP_INSTALL pytest-xdist; fi
 
     # ASTROPY
diff --git a/pvextractor/geometry/poly_slices.py b/pvextractor/geometry/poly_slices.py
index 6fb00dfcdf..a91afc0353 100644
--- a/pvextractor/geometry/poly_slices.py
+++ b/pvextractor/geometry/poly_slices.py
@@ -41,8 +41,11 @@ def extract_poly_slice(cube, polygons):
                                                    polygon.x, polygon.y)
 
                 if area > 0:
-                    total_slice[:, i] += cube[:, ymin, xmin] * area
-                    total_area[:, i] += area
+                    dataslice = cube[:, ymin, xmin]
+                    good_values = np.isfinite(dataslice)
+                    if np.any(good_values):
+                        total_slice[good_values, i] += dataslice[good_values] * area
+                        total_area[good_values, i] += area
 
     total_slice[total_area == 0.] = np.nan
     total_slice[total_area > 0.] /= total_area[total_area > 0.]
diff --git a/pvextractor/tests/test_slicer.py b/pvextractor/tests/test_slicer.py
index d6df8859da..e51ec01e85 100644
--- a/pvextractor/tests/test_slicer.py
+++ b/pvextractor/tests/test_slicer.py
@@ -74,7 +74,6 @@
 LONPOLE =                180.0 / [deg] Native longitude of celestial pole
 LATPOLE =        30.5765277962 / [deg] Native latitude of celestial pole
 RESTFRQ =        1420405718.41 / [Hz] Line rest frequency
-EQUINOX =               2000.0 / [yr] Equinox of equatorial coordinates
 SPECSYS = 'BARYCENT'           / Reference frame of spectral coordinates
 MJD-OBS =         50982.687794 / [d] MJD of observation matching DATE-OBS
 DATE-OBS= '1998-06-18T16:30:25.4' / ISO-8601 observation date matching MJD-OBS