diff --git a/scripts/mbedtls_dev/bignum_mod.py b/scripts/mbedtls_dev/bignum_mod.py
index aa06fe8..9086c2e 100644
--- a/scripts/mbedtls_dev/bignum_mod.py
+++ b/scripts/mbedtls_dev/bignum_mod.py
@@ -55,6 +55,20 @@
 # END MERGE SLOT 4
 
 # BEGIN MERGE SLOT 5
+class BignumModAdd(bignum_common.ModOperationCommon, BignumModTarget):
+    """Test cases for bignum mpi_mod_add()."""
+    count = 0
+    symbol = "+"
+    test_function = "mpi_mod_add"
+    test_name = "mbedtls_mpi_mod_add"
+    input_style = "fixed"
+
+    def result(self) -> List[str]:
+        result = (self.int_a + self.int_b) % self.int_n
+        # To make negative tests easier, append "0" for success to the
+        # generated cases
+        return [self.format_result(result), "0"]
+
 
 # END MERGE SLOT 5