diff --git a/postprocessor.py b/postprocessor.py
index 65a1927..61a2882 100644
--- a/postprocessor.py
+++ b/postprocessor.py
@@ -891,7 +891,7 @@ class PostProcessor(HDF5Container):
             # Get coordinates
             im_extent = np.array(self.save.root.maps._v_attrs.im_extent) * self.lbox
             map_size = self.pp_params.pymses.map_size
-            center = self.pp_params.disk.center * self.lbox
+            center = np.array(self.pp_params.disk.center) * self.lbox
 
             # Physical size of cells
             dx = (im_extent[1] - im_extent[0]) / map_size
@@ -918,7 +918,7 @@ class PostProcessor(HDF5Container):
         """
         Computes radial bins (for disk)
         """
-        center = self.pp_params.disk.center * self.lbox
+        center = np.array(self.pp_params.disk.center) * self.lbox
         im_extent = np.array(self.save.root.maps._v_attrs.im_extent) * self.lbox
 
         # radius of the corner of the box plus a margin
@@ -959,7 +959,7 @@ class PostProcessor(HDF5Container):
         """
         im_extent = np.array(self.save.root.maps._v_attrs.im_extent) * self.lbox
         map_size = self.pp_params.pymses.map_size
-        center = self.pp_params.disk.center * self.lbox
+        center = np.array(self.pp_params.disk.center) * self.lbox
 
         # Physical size of cells
         dx = (im_extent[1] - im_extent[0]) / map_size
@@ -1296,7 +1296,7 @@ class PostProcessor(HDF5Container):
         # Get coordinates
         im_extent = np.array(self.save.root.maps._v_attrs.im_extent) * self.lbox
         map_size = self.pp_params.pymses.map_size
-        center = self.pp_params.disk.center * self.lbox
+        center = np.array(self.pp_params.disk.center) * self.lbox
 
         # Physical size of cells
         dx = (im_extent[1] - im_extent[0]) / map_size