diff --git a/doc/tutorials/12-constant_pH/12-constant_pH.ipynb b/doc/tutorials/12-constant_pH/12-constant_pH.ipynb
index 96667cb798f..19f76b21b94 100644
--- a/doc/tutorials/12-constant_pH/12-constant_pH.ipynb
+++ b/doc/tutorials/12-constant_pH/12-constant_pH.ipynb
@@ -170,7 +170,9 @@
     "\n",
     "# dependent parameters\n",
     "Box_V = (N_acid/N_A/c_acid)\n",
-    "Box_L = np.cbrt(Box_V.to('m**3'))*ureg('m')\n",
+    "Box_L = np.cbrt(Box_V.to('m**3'))\n",
+    "if tuple(map(int, pint.__version__.split('.'))) < (0, 10):\n",
+    "    Box_L *= ureg('m')\n",
     "# we shall often need the numerical value of box length in sigma\n",
     "Box_L_in_sigma = Box_L.to('sigma').magnitude\n",
     "# unfortunately, pint module cannot handle cube root of m**3, so we need to explicitly set the unit\n",