diff --git a/docs/usage/dynamics/k-matrix.ipynb b/docs/usage/dynamics/k-matrix.ipynb
index b401194e2..24dd7bd89 100644
--- a/docs/usage/dynamics/k-matrix.ipynb
+++ b/docs/usage/dynamics/k-matrix.ipynb
@@ -642,9 +642,9 @@
    "outputs": [],
    "source": [
     "# reformulate terms\n",
-    "denominator, nominator = k_matrix.args\n",
-    "term1 = nominator.args[0] * denominator\n",
-    "term2 = nominator.args[1] * denominator\n",
+    "*rest, denominator, nominator = k_matrix.args\n",
+    "term1 = nominator.args[0] * denominator * sp.Mul(*rest)\n",
+    "term2 = nominator.args[1] * denominator * sp.Mul(*rest)\n",
     "k_matrix = term1 + term2\n",
     "k_matrix"
    ]
@@ -934,9 +934,9 @@
     "    sp.sqrt(rho): 1,\n",
     "    sp.conjugate(sp.sqrt(rho)): 1,\n",
     "})\n",
-    "denominator, nominator = rel_k_matrix_2r.args\n",
-    "term1 = nominator.args[0] * denominator\n",
-    "term2 = nominator.args[1] * denominator\n",
+    "*rest, denominator, nominator = rel_k_matrix_2r.args\n",
+    "term1 = nominator.args[0] * denominator * sp.Mul(*rest)\n",
+    "term2 = nominator.args[1] * denominator * sp.Mul(*rest)\n",
     "rel_k_matrix_2r = term1 + term2\n",
     "rel_k_matrix_2r"
    ]
@@ -1081,9 +1081,9 @@
    },
    "outputs": [],
    "source": [
-    "denominator, nominator = f_vector.args\n",
-    "term1 = nominator.args[0] * denominator\n",
-    "term2 = nominator.args[1] * denominator\n",
+    "*rest, denominator, nominator = f_vector.args\n",
+    "term1 = nominator.args[0] * denominator * sp.Mul(*rest)\n",
+    "term2 = nominator.args[1] * denominator * sp.Mul(*rest)\n",
     "f_vector = term1 + term2\n",
     "f_vector"
    ]
diff --git a/tests/dynamics/test_kmatrix.py b/tests/dynamics/test_kmatrix.py
index 0d1f1ddf2..bd37c3baa 100644
--- a/tests/dynamics/test_kmatrix.py
+++ b/tests/dynamics/test_kmatrix.py
@@ -1,16 +1,13 @@
 from __future__ import annotations
 
 import re
-from typing import TYPE_CHECKING
 
 import pytest
+import sympy as sp
 
 from ampform.dynamics.kmatrix import NonRelativisticKMatrix
 from symplot import rename_symbols, substitute_indexed_symbols
 
-if TYPE_CHECKING:
-    import sympy as sp
-
 
 class TestNonRelativisticKMatrix:
     @pytest.mark.parametrize(
@@ -35,9 +32,9 @@ def test_interference_single_channel(self):
         expr = substitute_indexed_symbols(expr)
         expr = _remove_residue_constants(expr)
         expr = _rename_widths(expr)
-        denominator, nominator = expr.args
-        term1 = nominator.args[0] * denominator
-        term2 = nominator.args[1] * denominator
+        *rest, denominator, nominator = expr.args
+        term1 = nominator.args[0] * denominator * sp.Mul(*rest)
+        term2 = nominator.args[1] * denominator * sp.Mul(*rest)
         assert str(term1 / term2) == R"m1*w1*(m2**2 - s)/(m2*w2*(m1**2 - s))"