diff --git a/rustler/src/dynamic.rs b/rustler/src/dynamic.rs
index 0a3996f0..47e89176 100644
--- a/rustler/src/dynamic.rs
+++ b/rustler/src/dynamic.rs
@@ -1,5 +1,10 @@
 #[cfg(feature = "nif_version_2_15")]
-use rustler_sys::ErlNifTermType;
+use rustler_sys::{
+    ErlNifTermType, ERL_NIF_TERM_TYPE_ATOM, ERL_NIF_TERM_TYPE_BITSTRING, ERL_NIF_TERM_TYPE_FLOAT,
+    ERL_NIF_TERM_TYPE_FUN, ERL_NIF_TERM_TYPE_INTEGER, ERL_NIF_TERM_TYPE_LIST,
+    ERL_NIF_TERM_TYPE_MAP, ERL_NIF_TERM_TYPE_PID, ERL_NIF_TERM_TYPE_PORT,
+    ERL_NIF_TERM_TYPE_REFERENCE, ERL_NIF_TERM_TYPE_TUPLE,
+};
 
 use crate::wrapper::check;
 use crate::Term;
@@ -23,7 +28,6 @@ pub enum TermType {
 #[cfg(feature = "nif_version_2_15")]
 impl From<ErlNifTermType> for TermType {
     fn from(term_type: ErlNifTermType) -> Self {
-        use ErlNifTermType::*;
         use TermType::*;
         match term_type {
             ERL_NIF_TERM_TYPE_ATOM => Atom,
diff --git a/rustler_sys/src/rustler_sys_api.rs b/rustler_sys/src/rustler_sys_api.rs
index ab15827b..50abaad8 100644
--- a/rustler_sys/src/rustler_sys_api.rs
+++ b/rustler_sys/src/rustler_sys_api.rs
@@ -308,28 +308,39 @@ pub enum ErlNifHash {
 
 /// See [ErlNifTermType](http://www.erlang.org/doc/man/erl_nif.html#ErlNifTermType) in the Erlang docs.
 #[cfg(feature = "nif_version_2_15")]
-#[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,
-}
+pub type ErlNifTermType = c_int;
+
+// from https://github.com/erlang/otp/blob/6618ce7b6a621e92db72ea4f01f7d38553c8818c/erts/emulator/beam/erl_nif.h#L291
+#[cfg(feature = "nif_version_2_15")]
+pub const ERL_NIF_TERM_TYPE_ATOM: ErlNifTermType = 1;
+#[cfg(feature = "nif_version_2_15")]
+pub const ERL_NIF_TERM_TYPE_BITSTRING: ErlNifTermType = 2;
+#[cfg(feature = "nif_version_2_15")]
+pub const ERL_NIF_TERM_TYPE_FLOAT: ErlNifTermType = 3;
+#[cfg(feature = "nif_version_2_15")]
+pub const ERL_NIF_TERM_TYPE_FUN: ErlNifTermType = 4;
+#[cfg(feature = "nif_version_2_15")]
+pub const ERL_NIF_TERM_TYPE_INTEGER: ErlNifTermType = 5;
+#[cfg(feature = "nif_version_2_15")]
+pub const ERL_NIF_TERM_TYPE_LIST: ErlNifTermType = 6;
+#[cfg(feature = "nif_version_2_15")]
+pub const ERL_NIF_TERM_TYPE_MAP: ErlNifTermType = 7;
+#[cfg(feature = "nif_version_2_15")]
+pub const ERL_NIF_TERM_TYPE_PID: ErlNifTermType = 8;
+#[cfg(feature = "nif_version_2_15")]
+pub const ERL_NIF_TERM_TYPE_PORT: ErlNifTermType = 9;
+#[cfg(feature = "nif_version_2_15")]
+pub const ERL_NIF_TERM_TYPE_REFERENCE: ErlNifTermType = 10;
+#[cfg(feature = "nif_version_2_15")]
+pub const ERL_NIF_TERM_TYPE_TUPLE: ErlNifTermType = 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. */
+#[allow(non_upper_case_globals)]
+#[cfg(feature = "nif_version_2_15")]
+pub const ERL_NIF_TERM_TYPE__MISSING_DEFAULT_CASE__READ_THE_MANUAL: ErlNifTermType = -1;
 
 /// See [ErlNifOption](http://www.erlang.org/doc/man/erl_nif.html#ErlNifOption) in the Erlang docs.
 #[cfg(feature = "nif_version_2_17")]