diff -urN pyNFFT-1.3.2-orig/pynfft/cnfft3util.pxd pyNFFT-1.3.2/pynfft/cnfft3util.pxd
--- pyNFFT-1.3.2-orig/pynfft/cnfft3util.pxd	2018-10-09 16:41:15.499575151 -0400
+++ pyNFFT-1.3.2/pynfft/cnfft3util.pxd	2018-10-09 16:41:38.394788488 -0400
@@ -17,7 +17,7 @@
 
 from cnfft3 cimport fftw_complex
 
-cdef extern from "nfft3util.h":
+cdef extern from "nfft3.h":
 
     void nfft_vrand_unit_complex (fftw_complex *x, int n)
  	    # Inits a vector of random complex numbers in \
@@ -29,6 +29,3 @@
     void nfft_voronoi_weights_1d (double *w, double *x, int M)
  	    # Computes non periodic voronoi weights, \
         # assumes ordered nodes $x_j$.
-
-    void nfft_voronoi_weights_S2(double *w, double *xi, int M)
-        # Computes voronoi weights for nodes on the sphere S^2. */
diff -urN pyNFFT-1.3.2-orig/pynfft/util.pyx pyNFFT-1.3.2/pynfft/util.pyx
--- pyNFFT-1.3.2-orig/pynfft/util.pyx	2018-10-09 16:41:15.499575151 -0400
+++ pyNFFT-1.3.2/pynfft/util.pyx	2018-10-09 16:42:25.604505154 -0400
@@ -64,20 +64,3 @@
                          (%d, %d)'%(w.size, x.size))
     nfft_voronoi_weights_1d(<double *>&w[0], <double *>&x[0], w.size)
 
-def voronoi_weights_S2 (object[np.float64_t, mode='c'] w not None,
-                        object[np.float64_t, mode='c'] xi not None):
-    '''
-    Utilitary function for computing density compensation weights from knots
-    located on the surface of a sphere.
-
-    Useful for reconstruction of 3D radial data.
-
-    :param w: pre-allocated array
-    :type w: ndarray <float64>
-    :param xi: angular locations (2D) on the unit sphere
-    :type xi: ndarray <float64>
-    '''
-    if xi.size != 2 * w.size:
-        raise ValueError('Incompatible size between weights and nodes \
-                         (%d, %d)'%(w.size, xi.size))
-    nfft_voronoi_weights_S2(<double *>&w[0], <double *>&xi[0], w.size)