diff --git a/sfs/fd/wfs.py b/sfs/fd/wfs.py
index 44fb2c6..840b59e 100644
--- a/sfs/fd/wfs.py
+++ b/sfs/fd/wfs.py
@@ -32,7 +32,6 @@ def plot(d, selection, secondary_source):
 
 """
 import numpy as _np
-from numpy.core.umath_tests import inner1d as _inner1d
 from scipy.special import hankel2 as _hankel2
 
 from . import secondary_source_line as _secondary_source_line
@@ -91,7 +90,7 @@ def line_2d(omega, x0, n0, xs, *, c=None):
     k = _util.wavenumber(omega, c)
     ds = x0 - xs
     r = _np.linalg.norm(ds, axis=1)
-    d = -1j/2 * k * _inner1d(ds, n0) / r * _hankel2(1, k * r)
+    d = -1j/2 * k * _util._inner1d(ds, n0) / r * _hankel2(1, k * r)
     selection = _util.source_selection_line(n0, x0, xs)
     return d, selection, _secondary_source_line(omega, c)
 
@@ -147,7 +146,7 @@ def _point(omega, x0, n0, xs, *, c=None):
     k = _util.wavenumber(omega, c)
     ds = x0 - xs
     r = _np.linalg.norm(ds, axis=1)
-    d = 1j * k * _inner1d(ds, n0) / r ** (3 / 2) * _np.exp(-1j * k * r)
+    d = 1j * k * _util._inner1d(ds, n0) / r ** (3 / 2) * _np.exp(-1j * k * r)
     selection = _util.source_selection_point(n0, x0, xs)
     return d, selection, _secondary_source_point(omega, c)
 
@@ -234,7 +233,7 @@ def point_25d(omega, x0, n0, xs, xref=[0, 0, 0], c=None, omalias=None):
         preeq_25d(omega, omalias, c) *
         _np.sqrt(8 * _np.pi) *
         _np.sqrt((r * s) / (r + s)) *
-        _inner1d(n0, ds) / s *
+        _util._inner1d(n0, ds) / s *
         _np.exp(-1j * k * s) / (4 * _np.pi * s))
     selection = _util.source_selection_point(n0, x0, xs)
     return d, selection, _secondary_source_point(omega, c)
@@ -316,7 +315,7 @@ def point_25d_legacy(omega, x0, n0, xs, xref=[0, 0, 0], c=None, omalias=None):
     r = _np.linalg.norm(ds, axis=1)
     d = (
         preeq_25d(omega, omalias, c) *
-        _np.sqrt(_np.linalg.norm(xref - x0)) * _inner1d(ds, n0) /
+        _np.sqrt(_np.linalg.norm(xref - x0)) * _util._inner1d(ds, n0) /
         r ** (3 / 2) * _np.exp(-1j * k * r))
     selection = _util.source_selection_point(n0, x0, xs)
     return d, selection, _secondary_source_point(omega, c)
@@ -499,7 +498,7 @@ def _focused(omega, x0, n0, xs, ns, *, c=None):
     k = _util.wavenumber(omega, c)
     ds = x0 - xs
     r = _np.linalg.norm(ds, axis=1)
-    d = 1j * k * _inner1d(ds, n0) / r ** (3 / 2) * _np.exp(1j * k * r)
+    d = 1j * k * _util._inner1d(ds, n0) / r ** (3 / 2) * _np.exp(1j * k * r)
     selection = _util.source_selection_focused(ns, x0, xs)
     return d, selection, _secondary_source_point(omega, c)
 
@@ -569,7 +568,7 @@ def focused_25d(omega, x0, n0, xs, ns, *, xref=[0, 0, 0], c=None,
     r = _np.linalg.norm(ds, axis=1)
     d = (
         preeq_25d(omega, omalias, c) *
-        _np.sqrt(_np.linalg.norm(xref - x0)) * _inner1d(ds, n0) /
+        _np.sqrt(_np.linalg.norm(xref - x0)) * _util._inner1d(ds, n0) /
         r ** (3 / 2) * _np.exp(1j * k * r))
     selection = _util.source_selection_focused(ns, x0, xs)
     return d, selection, _secondary_source_point(omega, c)
diff --git a/sfs/td/wfs.py b/sfs/td/wfs.py
index 3b59301..3e11208 100644
--- a/sfs/td/wfs.py
+++ b/sfs/td/wfs.py
@@ -44,7 +44,6 @@ def plot(d, selection, secondary_source, t=0):
 
 """
 import numpy as _np
-from numpy.core.umath_tests import inner1d as _inner1d
 
 from . import apply_delays as _apply_delays
 from . import secondary_source_point as _secondary_source_point
@@ -119,8 +118,8 @@ def plane_25d(x0, n0, n=[0, 1, 0], xref=[0, 0, 0], c=None):
     n = _util.normalize_vector(n)
     xref = _util.asarray_1d(xref)
     g0 = _np.sqrt(2 * _np.pi * _np.linalg.norm(xref - x0, axis=1))
-    delays = _inner1d(n, x0) / c
-    weights = 2 * g0 * _inner1d(n, n0)
+    delays = _util._inner1d(n, x0) / c
+    weights = 2 * g0 * _util._inner1d(n, n0)
     selection = _util.source_selection_plane(n0, n)
     return delays, weights, selection, _secondary_source_point(c)
 
@@ -208,7 +207,7 @@ def point_25d(x0, n0, xs, xref=[0, 0, 0], c=None):
     g0 *= _np.sqrt((x0xs_n*x0xref_n)/(x0xs_n+x0xref_n))
 
     delays = x0xs_n/c
-    weights = g0*_inner1d(x0xs, n0)
+    weights = g0 * _util._inner1d(x0xs, n0)
     selection = _util.source_selection_point(n0, x0, xs)
     return delays, weights, selection, _secondary_source_point(c)
 
@@ -296,7 +295,7 @@ def point_25d_legacy(x0, n0, xs, xref=[0, 0, 0], c=None):
     ds = x0 - xs
     r = _np.linalg.norm(ds, axis=1)
     delays = r/c
-    weights = g0 * _inner1d(ds, n0) / (2 * _np.pi * r**(3/2))
+    weights = g0 * _util._inner1d(ds, n0) / (2 * _np.pi * r**(3/2))
     selection = _util.source_selection_point(n0, x0, xs)
     return delays, weights, selection, _secondary_source_point(c)
 
@@ -379,7 +378,7 @@ def focused_25d(x0, n0, xs, ns, xref=[0, 0, 0], c=None):
     g0 = _np.sqrt(_np.linalg.norm(xref - x0, axis=1)
                   / (_np.linalg.norm(xref - x0, axis=1) + r))
     delays = -r/c
-    weights = g0 * _inner1d(ds, n0) / (2 * _np.pi * r**(3/2))
+    weights = g0 * _util._inner1d(ds, n0) / (2 * _np.pi * r**(3/2))
     selection = _util.source_selection_focused(ns, x0, xs)
     return delays, weights, selection, _secondary_source_point(c)