diff --git a/c_src/encoder.c b/c_src/encoder.c
index e864777..3ee1f59 100644
--- a/c_src/encoder.c
+++ b/c_src/encoder.c
@@ -814,9 +814,25 @@ encode_iter(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
                 ret = enc_obj_error(e, "invalid_object_member_arity", item);
                 goto done;
             }
-            if(!enc_string(e, tuple[0])) {
-                ret = enc_obj_error(e, "invalid_object_member_key", tuple[0]);
-                goto done;
+            if(enif_get_int64(env, tuple[0], &lval)) {
+                if (!enc_char(e, '"')) {
+                    ret = enc_error(e, "internal_error");
+                    goto done;
+                }
+                if(!enc_long(e, lval)) {
+                    ret = enc_obj_error(e, "invalid_object_member_key", tuple[0]);
+                    goto done;
+                }
+                if (!enc_char(e, '"')) {
+                    ret = enc_error(e, "internal_error");
+                    goto done;
+                }
+            }
+            else {
+                if(!enc_string(e, tuple[0])) {
+                    ret = enc_obj_error(e, "invalid_object_member_key", tuple[0]);
+                    goto done;
+                }
             }
             if(!enc_colon(e)) {
                 ret = enc_error(e, "internal_error");