diff --git a/pyFAI/utils/mathutil.py b/pyFAI/utils/mathutil.py
index f65eac2dd..3ea250e05 100644
--- a/pyFAI/utils/mathutil.py
+++ b/pyFAI/utils/mathutil.py
@@ -43,8 +43,8 @@
 import math
 import numpy
 import time
+import scipy.ndimage
 from .decorators import deprecated
-scipy = None
 
 try:
     from ..ext import relabel as _relabel
@@ -141,9 +141,6 @@ def gaussian_filter(input_img, sigma, mode="reflect", cval=0.0, use_scipy=True):
         Value to fill past edges of input if ``mode`` is 'constant'. Default is 0.0
     """
     if use_scipy:
-        global scipy
-        if scipy is None:
-            import scipy.ndimage
         res = scipy.ndimage.filters.gaussian_filter(input_img, sigma, mode=(mode or "reflect"))
     else:
         if isinstance(sigma, (list, tuple)):
@@ -416,9 +413,6 @@ def shift_fft(input_img, shift_val, method="fft"):
         e = e0 * e1
         out = abs(numpy.fft.ifft2(numpy.fft.fft2(input_img) * e))
     else:
-        global scipy
-        if scipy is None:
-            import scipy.ndimage
         out = scipy.ndimage.interpolation.shift(input, shift, mode="wrap", order="infinity")
     return out
 
diff --git a/pyproject.toml b/pyproject.toml
index aee1cd3fb..ff6aac639 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -37,7 +37,13 @@ classifiers = ["Development Status :: 5 - Production/Stable",
                ]
 
 dependencies = [
-   'numpy', 'h5py', 'fabio', 'silx', 'numexpr'
+   'numpy',
+   'h5py',
+   'fabio',
+   'silx',
+   'numexpr',
+   'scipy',
+   'matplotlib'
 ]
 
 [build-system]