diff --git a/tests/suites/test_suite_dhm.function b/tests/suites/test_suite_dhm.function
index dad6be1..8a05a38 100644
--- a/tests/suites/test_suite_dhm.function
+++ b/tests/suites/test_suite_dhm.function
@@ -14,6 +14,7 @@
     unsigned char buf[42] = { 0 };
     unsigned char *buf_null = NULL;
     mbedtls_mpi X;
+    size_t const buflen = sizeof( buf );
     size_t len;
 
     TEST_INVALID_PARAM( mbedtls_dhm_init( NULL ) );
@@ -33,22 +34,22 @@
                                                      NULL ) );
 
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_DHM_BAD_INPUT_DATA,
-                            mbedtls_dhm_make_params( NULL, 42,
+                            mbedtls_dhm_make_params( NULL, buflen,
                                                      buf, &len,
                                                      rnd_std_rand,
                                                      NULL ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_DHM_BAD_INPUT_DATA,
-                            mbedtls_dhm_make_params( &ctx, 42,
+                            mbedtls_dhm_make_params( &ctx, buflen,
                                                      NULL, &len,
                                                      rnd_std_rand,
                                                      NULL ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_DHM_BAD_INPUT_DATA,
-                            mbedtls_dhm_make_params( &ctx, 42,
+                            mbedtls_dhm_make_params( &ctx, buflen,
                                                      buf, NULL,
                                                      rnd_std_rand,
                                                      NULL ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_DHM_BAD_INPUT_DATA,
-                            mbedtls_dhm_make_params( &ctx, 42,
+                            mbedtls_dhm_make_params( &ctx, buflen,
                                                      buf, &len,
                                                      NULL,
                                                      NULL ) );
@@ -61,44 +62,44 @@
                             mbedtls_dhm_set_group( &ctx, &X, NULL ) );
 
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_DHM_BAD_INPUT_DATA,
-                            mbedtls_dhm_read_public( NULL, buf, 42 ) );
+                            mbedtls_dhm_read_public( NULL, buf, buflen ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_DHM_BAD_INPUT_DATA,
-                            mbedtls_dhm_read_public( &ctx, NULL, 42 ) );
+                            mbedtls_dhm_read_public( &ctx, NULL, buflen ) );
 
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_DHM_BAD_INPUT_DATA,
-                            mbedtls_dhm_make_public( NULL, 42,
-                                                     buf, 42,
+                            mbedtls_dhm_make_public( NULL, buflen,
+                                                     buf, buflen,
                                                      rnd_std_rand,
                                                      NULL ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_DHM_BAD_INPUT_DATA,
-                            mbedtls_dhm_make_public( &ctx, 42,
-                                                     NULL, 42,
+                            mbedtls_dhm_make_public( &ctx, buflen,
+                                                     NULL, buflen,
                                                      rnd_std_rand,
                                                      NULL ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_DHM_BAD_INPUT_DATA,
-                            mbedtls_dhm_make_public( &ctx, 42,
-                                                     buf, 42,
+                            mbedtls_dhm_make_public( &ctx, buflen,
+                                                     buf, buflen,
                                                      NULL,
                                                      NULL ) );
 
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_DHM_BAD_INPUT_DATA,
-                            mbedtls_dhm_calc_secret( NULL, buf, 42,
+                            mbedtls_dhm_calc_secret( NULL, buf, buflen,
                                                      &len, rnd_std_rand,
                                                      NULL ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_DHM_BAD_INPUT_DATA,
-                            mbedtls_dhm_calc_secret( &ctx, NULL, 42,
+                            mbedtls_dhm_calc_secret( &ctx, NULL, buflen,
                                                      &len, rnd_std_rand,
                                                      NULL ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_DHM_BAD_INPUT_DATA,
-                            mbedtls_dhm_calc_secret( &ctx, buf, 42,
+                            mbedtls_dhm_calc_secret( &ctx, buf, buflen,
                                                      NULL, rnd_std_rand,
                                                      NULL ) );
 
 #if defined(MBEDTLS_ASN1_PARSE_C)
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_DHM_BAD_INPUT_DATA,
-                            mbedtls_dhm_parse_dhm( NULL, buf, 42 ) );
+                            mbedtls_dhm_parse_dhm( NULL, buf, buflen ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_DHM_BAD_INPUT_DATA,
-                            mbedtls_dhm_parse_dhm( &ctx, NULL, 42 ) );
+                            mbedtls_dhm_parse_dhm( &ctx, NULL, buflen ) );
 
 #if defined(MBEDTLS_FS_IO)
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_DHM_BAD_INPUT_DATA,