diff --git a/fil_finder/filfinderPPP.py b/fil_finder/filfinderPPP.py
index 8d63e3e..4713045 100644
--- a/fil_finder/filfinderPPP.py
+++ b/fil_finder/filfinderPPP.py
@@ -106,7 +106,7 @@ def create_mask(self, adapt_thresh=9, glob_thresh=0.0,
             recomputing the mask.
 
         Attributes
-        ----------
+        -------
         mask : numpy.ndarray
             The mask of the filaments.
 
@@ -155,8 +155,9 @@ def create_mask(self, adapt_thresh=9, glob_thresh=0.0,
         close = mo.closing(dilate)
 
         # Don't allow small holes: these lead to "shell"-shaped skeleton features
-        mo.remove_small_objects(close, min_size=min_object_size, connectivity=1, in_place=True)
-        mo.remove_small_holes(close, area_threshold=max_hole_size, connectivity=1, in_place=True)
+        close = mo.remove_small_objects(close, min_size=min_object_size, connectivity=1)
+        mo.remove_small_holes(close, area_threshold=max_hole_size, connectivity=1)
+     
 
         self.mask = close
 
diff --git a/setup.cfg b/setup.cfg
index d95f47a..98f1daa 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -22,9 +22,9 @@ install_requires =
     networkx
     scipy
     matplotlib
-    scikit-image
+    scikit-image>=0.20.0
     h5py
-    skan
+    skan>=0.11.0
     numba
     pandas
 
@@ -47,7 +47,7 @@ testpaths = "fil_finder" "docs"
 astropy_header = true
 doctest_plus = enabled
 text_file_format = rst
-addopts =  -p no:warnings
+addopts = -p no:warnings
 
 [coverage:run]
 omit =