diff --git a/t/t_mpi.c b/t/t_mpi.c
index bcfa75c..3e72ba9 100644
--- a/t/t_mpi.c
+++ b/t/t_mpi.c
@@ -686,20 +686,22 @@ t_mpi_large_load_fail(char **desc CRYB_UNUSED, void *arg CRYB_UNUSED)
 
 static struct t_cmp_case {
 	const char *desc;
-	uint8_t a[16];
-	size_t alen;
-	uint8_t b[16];
-	size_t blen;
-	int cmpabs, cmp;
+	int a, b, cmp;
 } t_cmp_cases[] = {
-	{
-		"0 == 0",
-		{ 0x00, }, 1,
-		{ 0x00, }, 1,
-		0, 0,
-	},
+	{ "-1 == -1",	-1,	-1,	 0 },
+	{ "-1 < 0",	-1,	 0,	-1 },
+	{ "-1 < 1",	-1,	 1,	-1 },
+	{ "0 > -1",	 0,	-1,	 1 },
+	{ "0 == 0",	 0,	 0,	 0 },
+	{ "0 < 1",	 0,	 1,	-1 },
+	{ "1 > -1",	 1,	-1,	 1 },
+	{ "1 > 0",	 1,	 0,	 1 },
+	{ "1 == 1",	 1,	 1,	 0 },
 };
 
+/*
+ * Compare two MPIs
+ */
 static int
 t_mpi_cmp(char **desc CRYB_UNUSED, void *arg)
 {
@@ -707,9 +709,28 @@ t_mpi_cmp(char **desc CRYB_UNUSED, void *arg)
 	cryb_mpi a = CRYB_MPI_ZERO, b = CRYB_MPI_ZERO;
 	int ret = 1;
 
-	mpi_load(&a, tc->a, tc->alen);
-	mpi_load(&b, tc->b, tc->blen);
-	ret &= t_compare_i(tc->cmpabs, mpi_cmp_abs(&a, &b));
+	mpi_set(&a, tc->a);
+	mpi_set(&b, tc->b);
+	ret &= t_compare_i(tc->cmp, mpi_cmp(&a, &b));
+	mpi_destroy(&a);
+	mpi_destroy(&b);
+	return (ret);
+}
+
+/*
+ * Compare two MPIs with garbage past the msb
+ */
+static int
+t_mpi_cmp_garbage(char **desc CRYB_UNUSED, void *arg)
+{
+	struct t_cmp_case *tc = arg;
+	cryb_mpi a = CRYB_MPI_ZERO, b = CRYB_MPI_ZERO;
+	int ret = 1;
+
+	mpi_set(&a, tc->a);
+	a.words[1] = 2;
+	mpi_set(&b, tc->b);
+	b.words[1] = tc->cmp < 1 ? 1 : 3;
 	ret &= t_compare_i(tc->cmp, mpi_cmp(&a, &b));
 	mpi_destroy(&a);
 	mpi_destroy(&b);
@@ -1405,8 +1426,11 @@ t_prepare(int argc, char *argv[])
 	t_add_test(t_mpi_large_load_fail, NULL, "large load (failure)");
 
 	/* comparison */
-	for (i = 0; i < sizeof t_cmp_cases / sizeof t_cmp_cases[0]; ++i)
+	for (i = 0; i < sizeof t_cmp_cases / sizeof t_cmp_cases[0]; ++i) {
 		t_add_test(t_mpi_cmp, &t_cmp_cases[i], t_cmp_cases[i].desc);
+		t_add_test(t_mpi_cmp_garbage, &t_cmp_cases[i],
+		    "%s (trailing garbage)", t_cmp_cases[i].desc);
+	}
 
 	/* left / right shift */
 	for (i = 0; i < sizeof t_lsh_cases / sizeof t_lsh_cases[0]; ++i)