diff --git a/.travis.yml b/.travis.yml
index c979f722..0f7ed035 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -12,6 +12,8 @@ matrix:
       elixir: 1.7.4
     - otp_release: 21.3
       elixir: 1.8.1
+    - otp_release: 22.0
+      elixir: 1.8.1
 
 env:
   global:
diff --git a/erl_nif_sys/gen_api.erl b/erl_nif_sys/gen_api.erl
index 15afb02d..f208dc89 100644
--- a/erl_nif_sys/gen_api.erl
+++ b/erl_nif_sys/gen_api.erl
@@ -33,8 +33,15 @@ version_opts("2.13") -> [{major,2}, {minor,13}, exception, getenv, time,   % erl
 version_opts("2.14") -> [{major,2}, {minor,14}, exception, getenv, time,   % erlang 21.0
                         dirty_scheduler_opt, nif_2_11, nif_2_12, nif_2_13,
                         nif_2_14];
-version_opts(_) ->
-    io:format("Unsupported Erlang version.\n\nIs the erlang_nif-sys version up to date in the Cargo.toml?\nDoes 'cargo update' fix it?\nIf not please report at https://github.com/goertzenator/erlang_nif-sys.\n"),
+version_opts("2.15") -> [{major,2}, {minor,15}, exception, getenv, time,   % erlang 22.0
+                        dirty_scheduler_opt, nif_2_11, nif_2_12, nif_2_13,
+                        nif_2_14, nif_2_15];
+version_opts(Ver) ->
+    io:format(
+        "This OTP release uses the unsupported Erlang NIF version ~p.\n\n"
+        "Please report at https://github.com/rustlerium/rustler.\n",
+        [Ver]
+    ),
     halt(1).
 
 ulong_opts("4") -> [{ulongsize, 4}];
@@ -344,11 +351,24 @@ api_list(Opts) -> [
             {"", "dummy_enif_vfprintf",             ""},
             {"", "dummy_enif_vsnprintf",            ""},
 
-            {"c_int",  "enif_make_map_from_arrays", "env: *mut ErlNifEnv, keys: *const ERL_NIF_TERM, values: *const ERL_NIF_TERM, cnt: usize, map_out: *mut ERL_NIF_TERM"}
+            {"c_int", "enif_make_map_from_arrays", "env: *mut ErlNifEnv, keys: *const ERL_NIF_TERM, values: *const ERL_NIF_TERM, cnt: usize, map_out: *mut ERL_NIF_TERM"}
         ];
         false -> []
-    end.
+    end ++
+    case proplists:get_bool(nif_2_15, Opts) of
+        true -> [
+            {"ErlNifTermType", "enif_term_type", "env: *mut ErlNifEnv, term: *const ERL_NIF_TERM"},
 
+            {"c_int", "enif_compare_pids", "pid1: *const ErlNifPid, pid2: *const ErlNifPid"},
+            {"c_int", "enif_is_pid_undefined", "pid: *const ErlNifPid"},
+            {"", "enif_set_pid_undefined", "pid: *mut ErlNifPid"},
+            {"ERL_NIF_TERM", "enif_make_monitor_term", "env: *mut ErlNifEnv, mon: *const ErlNifMonitor"},
+
+            {"c_int", "enif_select_read", "env: *mut ErlNifEnv, e: ErlNifEvent, obj: *const c_void, pid: *const ErlNifPid, msg: *const ERL_NIF_TERM, msg_env: *mut ErlNifEnv"},
+            {"c_int", "enif_select_write", "env: *mut ErlNifEnv, e: ErlNifEvent, obj: *const c_void, pid: *const ErlNifPid, msg: *const ERL_NIF_TERM, msg_env: *mut ErlNifEnv"}
+        ];
+        false -> []
+    end.
 
 
 main([UlongSizeT]) -> main([UlongSizeT,"."]);
diff --git a/erl_nif_sys/src/erl_nif_sys_api.rs b/erl_nif_sys/src/erl_nif_sys_api.rs
index 34582dfa..4b6364bd 100644
--- a/erl_nif_sys/src/erl_nif_sys_api.rs
+++ b/erl_nif_sys/src/erl_nif_sys_api.rs
@@ -149,6 +149,9 @@ pub type ErlNifSelectFlags = c_int;
 pub const ERL_NIF_SELECT_READ: ErlNifSelectFlags = (1 << 0);
 pub const ERL_NIF_SELECT_WRITE: ErlNifSelectFlags = (1 << 1);
 pub const ERL_NIF_SELECT_STOP: ErlNifSelectFlags = (1 << 2);
+pub const ERL_NIF_SELECT_FAILED: ErlNifSelectFlags = (1 << 3);
+pub const ERL_NIF_SELECT_READ_CANCELLED: ErlNifSelectFlags = (1 << 4);
+pub const ERL_NIF_SELECT_WRITE_CANCELLED: ErlNifSelectFlags = (1 << 5);
 
 /// See [ErlNifMonitor](http://www.erlang.org/doc/man/erl_nif.html#ErlNifMonitor) in the Erlang docs.
 #[derive(Debug, Copy, Clone)]
@@ -288,6 +291,31 @@ pub enum ErlNifHash {
     ERL_NIF_PHASH2 = 2,
 }
 
+/// See [ErlNifTermType](http://www.erlang.org/doc/man/erl_nif.html#ErlNifTermType) in the Erlang docs.
+#[derive(Copy, Clone)]
+#[repr(C)]
+pub enum ErlNifTermType {
+    // from https://github.com/erlang/otp/blob/6618ce7b6a621e92db72ea4f01f7d38553c8818c/erts/emulator/beam/erl_nif.h#L291
+    ERL_NIF_TERM_TYPE_ATOM = 1,
+    ERL_NIF_TERM_TYPE_BITSTRING = 2,
+    ERL_NIF_TERM_TYPE_FLOAT = 3,
+    ERL_NIF_TERM_TYPE_FUN = 4,
+    ERL_NIF_TERM_TYPE_INTEGER = 5,
+    ERL_NIF_TERM_TYPE_LIST = 6,
+    ERL_NIF_TERM_TYPE_MAP = 7,
+    ERL_NIF_TERM_TYPE_PID = 8,
+    ERL_NIF_TERM_TYPE_PORT = 9,
+    ERL_NIF_TERM_TYPE_REFERENCE = 10,
+    ERL_NIF_TERM_TYPE_TUPLE = 11,
+
+    /* This is a dummy value intended to coax the compiler into warning about
+     * unhandled values in a switch even if all the above values have been
+     * handled. We can add new entries at any time so the user must always
+     * have a default case. */
+    ERL_NIF_TERM_TYPE__MISSING_DEFAULT_CASE__READ_THE_MANUAL = -1
+}
+
+
 include!(concat!(env!("OUT_DIR"), "/nif_api.snippet"));
 // example of included content:
 // extern "C" {
diff --git a/rustler/build.rs b/rustler/build.rs
index 2fac7827..118529f3 100644
--- a/rustler/build.rs
+++ b/rustler/build.rs
@@ -11,7 +11,7 @@ use which::which;
 lazy_static! {
     // keep this sorted by version number
     static ref NIF_VERSION: Vec<&'static str> = vec![
-        "2.7", "2.8", "2.9", "2.10", "2.11", "2.12", "2.13", "2.14"
+        "2.7", "2.8", "2.9", "2.10", "2.11", "2.12", "2.13", "2.14", "2.15"
     ];
 }
 
diff --git a/rustler_tests/test/resource_test.exs b/rustler_tests/test/resource_test.exs
index 376e741c..f66850e3 100644
--- a/rustler_tests/test/resource_test.exs
+++ b/rustler_tests/test/resource_test.exs
@@ -29,6 +29,7 @@ defmodule RustlerTest.ResourceTest do
 
     # Clean them up. Don't crash.
     :erlang.garbage_collect()
+    :timer.sleep(100)
 
     # Erlang's exact GC should have cleaned all that up.
     assert RustlerTest.resource_immutable_count() == 0