diff --git a/scripts/mbedtls_dev/bignum_common.py b/scripts/mbedtls_dev/bignum_common.py
index ed321d7c3e..6fd42d1e7f 100644
--- a/scripts/mbedtls_dev/bignum_common.py
+++ b/scripts/mbedtls_dev/bignum_common.py
@@ -273,6 +273,15 @@ class ModOperationCommon(OperationCommon):
             return False
         return True
 
+    @classmethod
+    def input_cases_args(cls) -> Iterator[Tuple[Any, Any, Any]]:
+        if cls.arity == 1:
+            yield from ((n, a, "0") for a, n in cls.input_cases)
+        elif cls.arity == 2:
+            yield from ((n, a, b) for a, b, n in cls.input_cases)
+        else:
+            raise ValueError("Unsupported number of operands!")
+
     @classmethod
     def generate_function_tests(cls) -> Iterator[test_case.TestCase]:
         if cls.input_style not in cls.input_styles:
@@ -284,14 +293,18 @@ class ModOperationCommon(OperationCommon):
                             for n in cls.moduli
                             for a, b in cls.get_value_pairs()
                             for bil in cls.limb_sizes)
+            special_cases = (cls(*args, bits_in_limb=bil)
+                             for args in cls.input_cases_args()
+                             for bil in cls.limb_sizes)
         else:
             test_objects = (cls(n, a, b)
                             for n in cls.moduli
                             for a, b in cls.get_value_pairs())
+            special_cases = (cls(*args) for args in cls.input_cases_args())
         yield from (valid_test_object.create_test_case()
                     for valid_test_object in filter(
                         lambda test_object: test_object.is_valid,
-                        test_objects
+                        chain(test_objects, special_cases)
                         ))
 
 # BEGIN MERGE SLOT 1