diff --git a/tests/unittests/tests-ipv6_addr/tests-ipv6_addr.c b/tests/unittests/tests-ipv6_addr/tests-ipv6_addr.c
index be72b3049e..4a459731f7 100644
--- a/tests/unittests/tests-ipv6_addr/tests-ipv6_addr.c
+++ b/tests/unittests/tests-ipv6_addr/tests-ipv6_addr.c
@@ -1026,6 +1026,22 @@ static void test_ipv6_addr_from_str__success6(void)
     TEST_ASSERT(ipv6_addr_equal(&a, &result));
 }
 
+static void test_ipv6_addr_split_iface__no_iface(void)
+{
+    char a[] = "fe80::f8f9:fafb:fcfd:feff";
+    TEST_ASSERT_NULL(ipv6_addr_split_iface(a));
+}
+
+static void test_ipv6_addr_split_iface__with_iface(void)
+{
+    char a[] = "fe80::f8f9:fafb:fcfd:feff%eth0";
+    char *iface = ipv6_addr_split_iface(a);
+    TEST_ASSERT_NOT_NULL(iface);
+    TEST_ASSERT_EQUAL_INT(strcmp("eth0", iface), 0);
+    /* check that the separator has been replaced with '\0' */
+    TEST_ASSERT_EQUAL_INT(*(iface - 1), '\0');
+}
+
 Test *tests_ipv6_addr_tests(void)
 {
     EMB_UNIT_TESTFIXTURES(fixtures) {
@@ -1114,6 +1130,8 @@ Test *tests_ipv6_addr_tests(void)
         new_TestFixture(test_ipv6_addr_from_str__success4),
         new_TestFixture(test_ipv6_addr_from_str__success5),
         new_TestFixture(test_ipv6_addr_from_str__success6),
+        new_TestFixture(test_ipv6_addr_split_iface__no_iface),
+        new_TestFixture(test_ipv6_addr_split_iface__with_iface),
     };
 
     EMB_UNIT_TESTCALLER(ipv6_addr_tests, NULL, NULL, fixtures);