diff --git a/src/cmc/bidimap.h b/src/cmc/bidimap.h
index cfe9213..ee4a52e 100644
--- a/src/cmc/bidimap.h
+++ b/src/cmc/bidimap.h
@@ -894,11 +894,15 @@ struct cmc_callbacks_bidimap
                                                                                \
     bool PFX##_contains_key(struct SNAME *_map_, K key)                        \
     {                                                                          \
+        _map_->flag = cmc_flags.OK;                                            \
+                                                                               \
         return PFX##_impl_get_entry_by_key(_map_, key) != NULL;                \
     }                                                                          \
                                                                                \
     bool PFX##_contains_val(struct SNAME *_map_, V val)                        \
     {                                                                          \
+        _map_->flag = cmc_flags.OK;                                            \
+                                                                               \
         return PFX##_impl_get_entry_by_val(_map_, val) != NULL;                \
     }                                                                          \
                                                                                \
diff --git a/src/cmc/multimap.h b/src/cmc/multimap.h
index 0cd666a..5c29624 100644
--- a/src/cmc/multimap.h
+++ b/src/cmc/multimap.h
@@ -1015,6 +1015,8 @@ struct cmc_callbacks_multimap
                                                                                \
     bool PFX##_contains(struct SNAME *_map_, K key)                            \
     {                                                                          \
+        _map_->flag = cmc_flags.OK;                                            \
+                                                                               \
         return PFX##_impl_get_entry(_map_, key) != NULL;                       \
     }                                                                          \
                                                                                \
diff --git a/tests/main/unt/bidimap.c b/tests/main/unt/bidimap.c
index a919c06..a078179 100644
--- a/tests/main/unt/bidimap.c
+++ b/tests/main/unt/bidimap.c
@@ -375,7 +375,7 @@ CMC_CREATE_UNIT(bidimap_test, true, {
 
         cmc_assert(!bm_insert(map, 1, 2));
         cmc_assert_equals(int32_t, cmc_flags.DUPLICATE, bm_flag(map));
-
+        map->flag = cmc_flags.ERROR;
         cmc_assert(!bm_insert(map, 2, 1));
         cmc_assert_equals(int32_t, cmc_flags.DUPLICATE, bm_flag(map));
 
@@ -394,6 +394,7 @@ CMC_CREATE_UNIT(bidimap_test, true, {
         cmc_assert(bm_insert(map, 2, 2));
         cmc_assert(!bm_update_key(map, 1, 2));
         cmc_assert_equals(int32_t, cmc_flags.DUPLICATE, bm_flag(map));
+        map->flag = cmc_flags.ERROR;
         cmc_assert(!bm_update_key(map, 2, 1));
         cmc_assert_equals(int32_t, cmc_flags.DUPLICATE, bm_flag(map));
 
@@ -412,6 +413,7 @@ CMC_CREATE_UNIT(bidimap_test, true, {
         cmc_assert(bm_insert(map, 2, 2));
         cmc_assert(!bm_update_key_by_val(map, 2, 1));
         cmc_assert_equals(int32_t, cmc_flags.DUPLICATE, bm_flag(map));
+        map->flag = cmc_flags.ERROR;
         cmc_assert(!bm_update_key_by_val(map, 1, 2));
         cmc_assert_equals(int32_t, cmc_flags.DUPLICATE, bm_flag(map));
 
@@ -430,6 +432,7 @@ CMC_CREATE_UNIT(bidimap_test, true, {
         cmc_assert(bm_insert(map, 2, 2));
         cmc_assert(!bm_update_val(map, 1, 2));
         cmc_assert_equals(int32_t, cmc_flags.DUPLICATE, bm_flag(map));
+        map->flag = cmc_flags.ERROR;
         cmc_assert(!bm_update_val(map, 2, 1));
         cmc_assert_equals(int32_t, cmc_flags.DUPLICATE, bm_flag(map));
 
@@ -448,6 +451,7 @@ CMC_CREATE_UNIT(bidimap_test, true, {
         cmc_assert(bm_insert(map, 2, 2));
         cmc_assert(!bm_update_val_by_key(map, 2, 1));
         cmc_assert_equals(int32_t, cmc_flags.DUPLICATE, bm_flag(map));
+        map->flag = cmc_flags.ERROR;
         cmc_assert(!bm_update_val_by_key(map, 1, 2));
         cmc_assert_equals(int32_t, cmc_flags.DUPLICATE, bm_flag(map));
 
@@ -480,14 +484,25 @@ CMC_CREATE_UNIT(bidimap_test, true, {
 
         cmc_assert_equals(size_t, 2, bm_get_key(map, 1));
         cmc_assert_equals(int32_t, cmc_flags.OK, bm_flag(map));
+        map->flag = cmc_flags.ERROR;
         cmc_assert_equals(size_t, 1, bm_get_val(map, 2));
         cmc_assert_equals(int32_t, cmc_flags.OK, bm_flag(map));
 
         cmc_assert_equals(size_t, 0, bm_get_key(map, 2));
         cmc_assert_equals(int32_t, cmc_flags.NOT_FOUND, bm_flag(map));
+        map->flag = cmc_flags.ERROR;
         cmc_assert_equals(size_t, 0, bm_get_val(map, 1));
         cmc_assert_equals(int32_t, cmc_flags.NOT_FOUND, bm_flag(map));
 
+        // contains_key
+        cmc_assert(bm_contains_key(map, 2));
+        cmc_assert_equals(int32_t, cmc_flags.OK, bm_flag(map));
+
+        // contains_val
+        map->flag = cmc_flags.ERROR;
+        cmc_assert(bm_contains_val(map, 1));
+        cmc_assert_equals(int32_t, cmc_flags.OK, bm_flag(map));
+
         // copy_of
         struct bidimap *map2 = bm_copy_of(map);
 
@@ -507,6 +522,7 @@ CMC_CREATE_UNIT(bidimap_test, true, {
         bm_get_key(map2, 100);
         cmc_assert_equals(int32_t, cmc_flags.NOT_FOUND, bm_flag(map));
         cmc_assert_equals(int32_t, cmc_flags.NOT_FOUND, bm_flag(map2));
+        map->flag = cmc_flags.ERROR;
         cmc_assert(bm_equals(map, map2));
         cmc_assert_equals(int32_t, cmc_flags.OK, bm_flag(map));
         cmc_assert_equals(int32_t, cmc_flags.OK, bm_flag(map2));
diff --git a/tests/main/unt/deque.c b/tests/main/unt/deque.c
index b0c10af..8c52602 100644
--- a/tests/main/unt/deque.c
+++ b/tests/main/unt/deque.c
@@ -659,15 +659,18 @@ CMC_CREATE_UNIT(deque_test, true, {
         cmc_assert_equals(int32_t, cmc_flags.OK, d_flag(d));
 
         // customize
+        d->flag = cmc_flags.ERROR;
         d_customize(d, &cmc_alloc_node_default,
                     &(struct cmc_callbacks_deque){ 0 });
         cmc_assert_equals(int32_t, cmc_flags.OK, d_flag(d));
 
         // push_front
+        d->flag = cmc_flags.ERROR;
         cmc_assert(d_push_front(d, 1));
         cmc_assert_equals(int32_t, cmc_flags.OK, d_flag(d));
 
         // pop_front
+        d->flag = cmc_flags.ERROR;
         cmc_assert(d_pop_front(d));
         cmc_assert_equals(int32_t, cmc_flags.OK, d_flag(d));
         cmc_assert(!d_pop_front(d));
@@ -678,20 +681,24 @@ CMC_CREATE_UNIT(deque_test, true, {
         cmc_assert_equals(int32_t, cmc_flags.OK, d_flag(d));
 
         // pop_back
+        d->flag = cmc_flags.ERROR;
         cmc_assert(d_pop_back(d));
         cmc_assert_equals(int32_t, cmc_flags.OK, d_flag(d));
         cmc_assert(!d_pop_back(d));
         cmc_assert_equals(int32_t, cmc_flags.EMPTY, d_flag(d));
 
         // front
+        d->flag = cmc_flags.ERROR;
         cmc_assert(d_front(d) == 0);
         cmc_assert_equals(int32_t, cmc_flags.EMPTY, d_flag(d));
 
         cmc_assert(d_push_back(d, 1));
+        d->flag = cmc_flags.ERROR;
         cmc_assert(d_front(d) == 1);
         cmc_assert_equals(int32_t, cmc_flags.OK, d_flag(d));
 
         // clear
+        d->flag = cmc_flags.ERROR;
         d_clear(d);
         cmc_assert_equals(int32_t, cmc_flags.OK, d_flag(d));
 
@@ -703,14 +710,23 @@ CMC_CREATE_UNIT(deque_test, true, {
         cmc_assert(d_back(d) == 1);
         cmc_assert_equals(int32_t, cmc_flags.OK, d_flag(d));
 
+        // contains
+        d->flag = cmc_flags.ERROR;
+        cmc_assert(d_contains(d, 1));
+        cmc_assert_equals(int32_t, cmc_flags.OK, d_flag(d));
+
         // copy_of
+        d->flag = cmc_flags.ERROR;
         struct deque *d2 = d_copy_of(d);
 
+        cmc_assert_equals(int32_t, cmc_flags.OK, d_flag(d));
         cmc_assert_equals(int32_t, cmc_flags.OK, d_flag(d2));
 
         // equals
         cmc_assert(d_pop_back(d));
         cmc_assert(d_pop_back(d2));
+        d->flag = cmc_flags.ERROR;
+        d2->flag = cmc_flags.ERROR;
         d_front(d);
         d_front(d2);
         cmc_assert_equals(int32_t, cmc_flags.EMPTY, d_flag(d));
diff --git a/tests/main/unt/multimap.c b/tests/main/unt/multimap.c
index 9baef6a..e3c9461 100644
--- a/tests/main/unt/multimap.c
+++ b/tests/main/unt/multimap.c
@@ -251,6 +251,11 @@ CMC_CREATE_UNIT(multimap_test, true, {
         mm_get_ref(map, 1);
         cmc_assert_equals(int32_t, cmc_flags.EMPTY, mm_flag(map));
 
+        // contains
+        map->flag = cmc_flags.ERROR;
+        cmc_assert(!mm_contains(map, 1000));
+        cmc_assert_equals(int32_t, cmc_flags.OK, mm_flag(map));
+
         // copy_of
         map->flag = cmc_flags.ERROR;
         struct multimap *map2 = mm_copy_of(map);