diff --git a/tests/suites/test_suite_ecp.data b/tests/suites/test_suite_ecp.data
index 93112002e..bbc8ea242 100644
--- a/tests/suites/test_suite_ecp.data
+++ b/tests/suites/test_suite_ecp.data
@@ -1039,3 +1039,5 @@ ECP check order for CURVE448
 depends_on:MBEDTLS_ECP_DP_CURVE448_ENABLED
 ecp_check_order:MBEDTLS_ECP_DP_CURVE448:"3fffffffffffffffffffffffffffffffffffffffffffffffffffffff7cca23e9c44edb49aed63690216cc2728dc58f552378c292ab5844f3"
 
+ECP quasi-reduction: uninitialized modulus
+ecp_quasi_reduction_neg:"11":"12":"1"
diff --git a/tests/suites/test_suite_ecp.function b/tests/suites/test_suite_ecp.function
index 394253de5..f5b581158 100644
--- a/tests/suites/test_suite_ecp.function
+++ b/tests/suites/test_suite_ecp.function
@@ -2,8 +2,7 @@
 #include "mbedtls/ecp.h"
 #include "mbedtls/ecdsa.h"
 #include "mbedtls/ecdh.h"
-
-#include "ecp_invasive.h"
+#include "ecp_internal.h"
 
 #if defined(MBEDTLS_TEST_HOOKS) &&                  \
     (defined(MBEDTLS_ECP_DP_SECP224R1_ENABLED) ||  \
@@ -1295,3 +1294,93 @@ exit:
     mbedtls_mpi_free(&expected_n);
 }
 /* END_CASE */
+
+/* BEGIN_CASE */
+void ecp_quasi_reduction(char *input_N,
+                         char *input_A,
+                         char *result)
+{
+    mbedtls_mpi_uint *A = NULL;
+    mbedtls_mpi_uint *N = NULL;
+    mbedtls_mpi_uint *res = NULL;
+    size_t limbs_A;
+    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(&A,   &limbs_A,   input_A), 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_A,   limbs);
+    TEST_EQUAL(limbs_res, limbs);
+
+    TEST_EQUAL(mbedtls_mpi_mod_modulus_setup(
+                   &m, N, limbs,
+                   MBEDTLS_MPI_MOD_REP_MONTGOMERY), 0);
+
+    TEST_EQUAL(mbedtls_ecp_quasi_reduction(A, &m), 0);
+    ASSERT_COMPARE(A, bytes, res, bytes);
+
+exit:
+    mbedtls_free(A);
+    mbedtls_free(res);
+
+    mbedtls_mpi_mod_modulus_free(&m);
+    mbedtls_free(N);
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void ecp_quasi_reduction_neg(char *input_N,
+                             char *input_A,
+                             char *result)
+{
+    mbedtls_mpi_uint *A = NULL;
+    mbedtls_mpi_uint *N = NULL;
+    mbedtls_mpi_uint *res = NULL;
+    size_t limbs_A;
+    size_t limbs_N;
+    size_t limbs_res;
+
+    mbedtls_mpi_mod_modulus m;
+    mbedtls_mpi_mod_modulus_init(&m);
+
+    mbedtls_mpi_mod_modulus fake_m;
+    mbedtls_mpi_mod_modulus_init(&fake_m);
+
+    TEST_EQUAL(mbedtls_test_read_mpi_core(&A,   &limbs_A,   input_A), 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_A,   limbs);
+    TEST_EQUAL(limbs_res, limbs);
+
+    TEST_EQUAL(mbedtls_mpi_mod_modulus_setup(
+                   &m, N, limbs,
+                   MBEDTLS_MPI_MOD_REP_MONTGOMERY), 0);
+
+    TEST_EQUAL(mbedtls_ecp_quasi_reduction(A, &m), 0);
+    ASSERT_COMPARE(A, bytes, res, bytes);
+
+    /* Check when m is not initialized */
+    TEST_EQUAL(mbedtls_ecp_quasi_reduction(A, &fake_m),
+               MBEDTLS_ERR_ECP_BAD_INPUT_DATA);
+
+exit:
+    mbedtls_free(A);
+    mbedtls_free(res);
+
+    mbedtls_mpi_mod_modulus_free(&fake_m);
+    mbedtls_mpi_mod_modulus_free(&m);
+    mbedtls_free(N);
+}
+/* END_CASE */