diff --git a/tests/unittests/tests-core/tests-core-cib.c b/tests/unittests/tests-core/tests-core-cib.c
index 487403ae84..fd371969a6 100644
--- a/tests/unittests/tests-core/tests-core-cib.c
+++ b/tests/unittests/tests-core/tests-core-cib.c
@@ -14,16 +14,15 @@
 
 #define TEST_CIB_SIZE  2
 
-cib_t cib;
+static cib_t cib;
 
 static void set_up(void)
 {
-    cib_init(&cib, 2);
+    cib_init(&cib, TEST_CIB_SIZE);
 }
 
 static void test_cib_put(void)
 {
-
     TEST_ASSERT_EQUAL_INT(0, cib_put(&cib));
     TEST_ASSERT_EQUAL_INT(1, cib_put(&cib));
     TEST_ASSERT_EQUAL_INT(-1, cib_put(&cib));
@@ -46,12 +45,44 @@ static void test_cib_avail(void)
     TEST_ASSERT_EQUAL_INT(2, cib_avail(&cib));
 }
 
+static void test_cib_put_and_get(void)
+{
+    TEST_ASSERT_EQUAL_INT(0, cib_put(&cib));
+    TEST_ASSERT_EQUAL_INT(0, cib_get(&cib));
+    TEST_ASSERT_EQUAL_INT(-1, cib_get(&cib));
+    TEST_ASSERT_EQUAL_INT(1, cib_put(&cib));
+    TEST_ASSERT_EQUAL_INT(0, cib_put(&cib));
+    TEST_ASSERT_EQUAL_INT(-1, cib_put(&cib));
+}
+
+static void test_empty_cib(void)
+{
+    cib_init(&cib, 0);
+    TEST_ASSERT_EQUAL_INT(0, cib_avail(&cib));
+    TEST_ASSERT_EQUAL_INT(-1, cib_get(&cib));
+    TEST_ASSERT_EQUAL_INT(-1, cib_put(&cib));
+}
+
+static void test_singleton_cib(void)
+{
+    cib_init(&cib, 1);
+    TEST_ASSERT_EQUAL_INT(0, cib_avail(&cib));
+    TEST_ASSERT_EQUAL_INT(-1, cib_get(&cib));
+    TEST_ASSERT_EQUAL_INT(0, cib_put(&cib));
+    TEST_ASSERT_EQUAL_INT(1, cib_avail(&cib));
+    TEST_ASSERT_EQUAL_INT(0, cib_get(&cib));
+    TEST_ASSERT_EQUAL_INT(0, cib_avail(&cib));
+}
+
 Test *tests_core_cib_tests(void)
 {
     EMB_UNIT_TESTFIXTURES(fixtures) {
         new_TestFixture(test_cib_put),
         new_TestFixture(test_cib_get),
         new_TestFixture(test_cib_avail),
+        new_TestFixture(test_cib_put_and_get),
+        new_TestFixture(test_empty_cib),
+        new_TestFixture(test_singleton_cib),
     };
 
     EMB_UNIT_TESTCALLER(core_cib_tests, set_up, NULL, fixtures);