diff --git a/lib/list.h b/lib/list.h
index fc0419da..8a5c165e 100644
--- a/lib/list.h
+++ b/lib/list.h
@@ -116,4 +116,37 @@ __END_EXTERN_C
         list_head_init((struct list_head *)(HEAD));                           \
         CHECK_TYPE(&(HEAD)->first, (HEAD)->tailnextp)
 
+/*
+ * LIST_SPLICE_TAIL/LIST_SPLICE_HEAD
+ *
+ * move all items on the SRC list to the TAIL/HEAD of the DST list.
+ * O(1) regardless of the number of items to move.
+ * this leaves the SRC list in an inconsistent state. it's up to
+ * the user to do LIST_HEAD_INIT(SRC) if necessary.
+ */
+
+#define LIST_SPLICE_TAIL(DST, SRC, NAME)                                      \
+        do {                                                                  \
+                if (!LIST_EMPTY(SRC)) {                                       \
+                        (SRC)->first->NAME.prevnextp = (DST)->tailnextp;      \
+                        *(DST)->tailnextp = (SRC)->first;                     \
+                        (DST)->tailnextp = (SRC)->tailnextp;                  \
+                }                                                             \
+        } while (0)
+
+#define LIST_SPLICE_HEAD(DST, SRC, NAME)                                      \
+        do {                                                                  \
+                if (!LIST_EMPTY(SRC)) {                                       \
+                        if (LIST_EMPTY(DST)) {                                \
+                                (DST)->tailnextp = (SRC)->tailnextp;          \
+                        } else {                                              \
+                                (DST)->first->NAME.prevnextp =                \
+                                        (SRC)->tailnextp;                     \
+                                *(SRC)->tailnextp = (DST)->first;             \
+                        }                                                     \
+                        (DST)->first = (SRC)->first;                          \
+                        (DST)->first->NAME.prevnextp = &(DST)->first;         \
+                }                                                             \
+        } while (0)
+
 #endif /* !defined(_TOYWASM_LIST_H) */
diff --git a/test/test.c b/test/test.c
index 6b4ffadf..f78bc0e4 100644
--- a/test/test.c
+++ b/test/test.c
@@ -767,6 +767,104 @@ test_list(void **state)
         assert_null(LIST_LAST(&h, struct item, entry));
 }
 
+void
+test_list2(void **state)
+{
+        struct item {
+                void *dummy1;
+                LIST_ENTRY(struct item) entry;
+                int dummy2;
+        };
+
+        LIST_HEAD(struct item) h0;
+        LIST_HEAD(struct item) h1;
+        LIST_HEAD(struct item) h2;
+        LIST_HEAD(struct item) hempty;
+
+        struct item i1;
+        struct item i2;
+        struct item i3;
+        struct item i4;
+        struct item i5;
+        struct item i6;
+
+        /* test LIST_SPLICE_TAIL */
+
+        LIST_HEAD_INIT(&h0);
+
+        LIST_HEAD_INIT(&h1);
+        LIST_INSERT_TAIL(&h1, &i1, entry);
+        LIST_INSERT_TAIL(&h1, &i2, entry);
+        LIST_INSERT_TAIL(&h1, &i3, entry);
+
+        LIST_HEAD_INIT(&h2);
+        LIST_INSERT_HEAD(&h2, &i6, entry);
+        LIST_INSERT_HEAD(&h2, &i5, entry);
+        LIST_INSERT_HEAD(&h2, &i4, entry);
+
+        LIST_HEAD_INIT(&hempty);
+        LIST_SPLICE_TAIL(&h0, &hempty, entry);
+        LIST_SPLICE_TAIL(&h0, &h1, entry);
+        LIST_HEAD_INIT(&hempty);
+        LIST_SPLICE_TAIL(&h0, &hempty, entry);
+        LIST_SPLICE_TAIL(&h0, &h2, entry);
+        LIST_HEAD_INIT(&hempty);
+        LIST_SPLICE_TAIL(&h0, &hempty, entry);
+
+        assert_ptr_equal(LIST_FIRST(&h0), &i1);
+        assert_ptr_equal(LIST_NEXT(&i1, entry), &i2);
+        assert_ptr_equal(LIST_NEXT(&i2, entry), &i3);
+        assert_ptr_equal(LIST_NEXT(&i3, entry), &i4);
+        assert_ptr_equal(LIST_NEXT(&i4, entry), &i5);
+        assert_ptr_equal(LIST_NEXT(&i5, entry), &i6);
+        assert_null(LIST_NEXT(&i6, entry));
+        assert_ptr_equal(LIST_LAST(&h0, struct item, entry), &i6);
+        assert_ptr_equal(LIST_PREV(&i6, &h0, struct item, entry), &i5);
+        assert_ptr_equal(LIST_PREV(&i5, &h0, struct item, entry), &i4);
+        assert_ptr_equal(LIST_PREV(&i4, &h0, struct item, entry), &i3);
+        assert_ptr_equal(LIST_PREV(&i3, &h0, struct item, entry), &i2);
+        assert_ptr_equal(LIST_PREV(&i2, &h0, struct item, entry), &i1);
+        assert_null(LIST_PREV(&i1, &h0, struct item, entry));
+
+        /* test LIST_SPLICE_HEAD */
+
+        LIST_HEAD_INIT(&h0);
+
+        LIST_HEAD_INIT(&h1);
+        LIST_INSERT_TAIL(&h1, &i1, entry);
+        LIST_INSERT_TAIL(&h1, &i2, entry);
+        LIST_INSERT_TAIL(&h1, &i3, entry);
+
+        LIST_HEAD_INIT(&h2);
+        LIST_INSERT_HEAD(&h2, &i6, entry);
+        LIST_INSERT_HEAD(&h2, &i5, entry);
+        LIST_INSERT_HEAD(&h2, &i4, entry);
+
+        LIST_HEAD_INIT(&hempty);
+        LIST_SPLICE_HEAD(&h0, &hempty, entry);
+        LIST_SPLICE_HEAD(&h0, &h1, entry);
+        LIST_HEAD_INIT(&hempty);
+        LIST_SPLICE_HEAD(&h0, &hempty, entry);
+        LIST_SPLICE_HEAD(&h0, &h2, entry);
+        LIST_HEAD_INIT(&hempty);
+        LIST_SPLICE_HEAD(&h0, &hempty, entry);
+
+        assert_ptr_equal(LIST_FIRST(&h0), &i4);
+        assert_ptr_equal(LIST_NEXT(&i4, entry), &i5);
+        assert_ptr_equal(LIST_NEXT(&i5, entry), &i6);
+        assert_ptr_equal(LIST_NEXT(&i6, entry), &i1);
+        assert_ptr_equal(LIST_NEXT(&i1, entry), &i2);
+        assert_ptr_equal(LIST_NEXT(&i2, entry), &i3);
+        assert_null(LIST_NEXT(&i3, entry));
+        assert_ptr_equal(LIST_LAST(&h0, struct item, entry), &i3);
+        assert_ptr_equal(LIST_PREV(&i3, &h0, struct item, entry), &i2);
+        assert_ptr_equal(LIST_PREV(&i2, &h0, struct item, entry), &i1);
+        assert_ptr_equal(LIST_PREV(&i1, &h0, struct item, entry), &i6);
+        assert_ptr_equal(LIST_PREV(&i6, &h0, struct item, entry), &i5);
+        assert_ptr_equal(LIST_PREV(&i5, &h0, struct item, entry), &i4);
+        assert_null(LIST_PREV(&i4, &h0, struct item, entry));
+}
+
 void
 test_xstrnstr(void **state)
 {
@@ -824,6 +922,7 @@ main(int argc, char **argv)
                 cmocka_unit_test(test_timeutil),
                 cmocka_unit_test(test_timeutil_int64),
                 cmocka_unit_test(test_list),
+                cmocka_unit_test(test_list2),
                 cmocka_unit_test(test_xstrnstr),
         };
         return cmocka_run_group_tests(tests, NULL, NULL);