diff --git a/lasp/wrappers.pyx b/lasp/wrappers.pyx
index 8d7d350..3c2698f 100644
--- a/lasp/wrappers.pyx
+++ b/lasp/wrappers.pyx
@@ -430,7 +430,9 @@ cdef extern from "lasp_sosfilterbank.h":
 cdef class SosFilterBank:
     cdef:
         c_Sosfilterbank* fb
+        us nsections
     def __cinit__(self,const us filterbank_size, const us nsections):
+        self.nsections = nsections
 
         self.fb = Sosfilterbank_create(0, filterbank_size,nsections)
 
@@ -441,11 +443,18 @@ cdef class SosFilterBank:
             filter_no: Filter number of the filterbank to set the
             filter for
             sos: Second axis are the filter coefficients, first axis 
-            is the section
+            is the section, second axis are the coefficients for that section.
+            Storage is in agreement with specification from Scipy: first axis
+            is the section, second axis are the coefficients for that section.
 
         """
+        if sos.shape[0] != self.nsections:
+            raise RuntimeError('Invalid number of sections in filter data, should be {self.nsections.}')
+        elif sos.shape[1] != 6:
+            raise RuntimeError('Illegal number of filter coefficients in section. Should be 6.')
         cdef dmat coefs = dmat_foreign_data(sos.size,1,
-                                            &sos[0, 0],False)
+                                            &sos[0, 0],False # No copying
+                                           )
         Sosfilterbank_setFilter(self.fb,filter_no, coefs)
 
     def __dealloc__(self):