diff --git a/tests/suites/test_suite_ecp.function b/tests/suites/test_suite_ecp.function
index b9d2b5e..b1a096d 100644
--- a/tests/suites/test_suite_ecp.function
+++ b/tests/suites/test_suite_ecp.function
@@ -4,8 +4,8 @@
 #include "mbedtls/ecdh.h"
 
 #include "bignum_core.h"
-#include "bignum_mod_raw_invasive.h"
 #include "ecp_invasive.h"
+#include "bignum_mod_raw_invasive.h"
 
 #if defined(MBEDTLS_TEST_HOOKS) &&                  \
     (defined(MBEDTLS_ECP_DP_SECP224R1_ENABLED) ||  \
@@ -1344,3 +1344,45 @@
     mbedtls_free(N);
 }
 /* END_CASE */
+
+/* BEGIN_CASE depends_on:MBEDTLS_TEST_HOOKS */
+void ecp_mod_p521_raw(char *input_N,
+                      char *input_X,
+                      char *result)
+{
+    mbedtls_mpi_uint *X = NULL;
+    mbedtls_mpi_uint *N = NULL;
+    mbedtls_mpi_uint *res = NULL;
+    size_t limbs_X;
+    size_t limbs_N;
+    size_t limbs_res;
+
+    mbedtls_mpi_mod_modulus m;
+    mbedtls_mpi_mod_modulus_init(&m);
+
+    TEST_EQUAL(mbedtls_test_read_mpi_core(&X,   &limbs_X,   input_X), 0);
+    TEST_EQUAL(mbedtls_test_read_mpi_core(&N,   &limbs_N,   input_N), 0);
+    TEST_EQUAL(mbedtls_test_read_mpi_core(&res, &limbs_res, result),  0);
+
+    size_t limbs = limbs_N;
+    size_t bytes = limbs * sizeof(mbedtls_mpi_uint);
+
+    TEST_EQUAL(limbs_X, 2 * limbs - 1);
+    TEST_EQUAL(limbs_res, limbs);
+
+    TEST_EQUAL(mbedtls_mpi_mod_modulus_setup(
+                   &m, N, limbs,
+                   MBEDTLS_MPI_MOD_REP_MONTGOMERY), 0);
+
+    TEST_EQUAL(ecp_mod_p521_raw(X, limbs_X), 0);
+    mbedtls_mpi_mod_raw_fix_quasi_reduction(X, &m);
+    ASSERT_COMPARE(X, bytes, res, bytes);
+
+exit:
+    mbedtls_free(X);
+    mbedtls_free(res);
+
+    mbedtls_mpi_mod_modulus_free(&m);
+    mbedtls_free(N);
+}
+/* END_CASE */