diff --git a/docs/reference/matrix-glib/matrix-glib-sections.txt b/docs/reference/matrix-glib/matrix-glib-sections.txt
index 6f29885..6c846ec 100644
--- a/docs/reference/matrix-glib/matrix-glib-sections.txt
+++ b/docs/reference/matrix-glib/matrix-glib-sections.txt
@@ -192,7 +192,6 @@ MATRIX_TYPE_API_PUSHER
 matrix_api_pusher_get_type
 MATRIX_TYPE_API_STATE_EVENT
 matrix_api_state_event_get_type
-g_enum_to_string
 </SECTION>
 
 <SECTION>
diff --git a/src/matrix-api-types.c b/src/matrix-api-types.c
index 0ab496d..b447275 100644
--- a/src/matrix-api-types.c
+++ b/src/matrix-api-types.c
@@ -43,6 +43,11 @@
  *                                 is not a JSON object
  * @MATRIX_API_ERROR_INVALID_ROOM_ID: the provided string doesn’t
  *                                    contain a valid room ID
+ * @MATRIX_API_ERROR_UNKNOWN_VALUE: the response from the Matrix.org
+ *                                  server contains a value unknown to
+ *                                  this library. These should be
+ *                                  reported to the Matrix GLib SDK
+ *                                  developers
  * @MATRIX_API_ERROR_MISSING_TOKEN: authorization token is missing
  *                                  from the request
  * @MATRIX_API_ERROR_FORBIDDEN: access was forbidden (e.g. due to a
@@ -1561,7 +1566,7 @@ matrix_api_filter_get_json_node(MatrixAPIFilter *filter)
 
     json_builder_set_member_name(builder, "event_format");
     json_builder_add_string_value(builder,
-                                  g_enum_to_string(
+                                  _g_enum_to_string(
                                           MATRIX_TYPE_API_EVENT_FORMAT,
                                           filter->event_format,
                                           TRUE));
diff --git a/src/matrix-api-types.h b/src/matrix-api-types.h
index c3b97a5..183f1f1 100644
--- a/src/matrix-api-types.h
+++ b/src/matrix-api-types.h
@@ -31,6 +31,7 @@ typedef enum {
     MATRIX_API_ERROR_BAD_REQUEST,
     MATRIX_API_ERROR_BAD_RESPONSE,
     MATRIX_API_ERROR_INVALID_ROOM_ID,
+    MATRIX_API_ERROR_UNKNOWN_VALUE,
 
     /* Add Matrix-defined error codes under here, changing `M_` to
      * `MATRIX_API_ERROR`, i.e. `M_FORBIDDEN` =>
diff --git a/src/matrix-http-api.c b/src/matrix-http-api.c
index 80ad628..92389f6 100644
--- a/src/matrix-http-api.c
+++ b/src/matrix-http-api.c
@@ -971,7 +971,7 @@ i_create_room(MatrixAPI *api,
     }
 
     if (preset != MATRIX_API_ROOM_PRESET_NONE) {
-        gchar *preset_string = g_enum_to_string(
+        gchar *preset_string = _g_enum_to_string(
                 MATRIX_TYPE_API_ROOM_PRESET, preset, TRUE);
 
        if (preset_string) {
@@ -994,7 +994,7 @@ i_create_room(MatrixAPI *api,
     }
 
     if (visibility != MATRIX_API_ROOM_VISIBILITY_DEFAULT) {
-        gchar *visibility_string = g_enum_to_string(
+        gchar *visibility_string = _g_enum_to_string(
                 MATRIX_TYPE_API_ROOM_VISIBILITY, visibility, TRUE);
 
         if (visibility_string) {
@@ -1348,7 +1348,7 @@ i_set_user_presence(MatrixAPI *api,
     json_builder_begin_object(builder);
 
     json_builder_set_member_name(builder, "presence");
-    presence_string = g_enum_to_string(MATRIX_TYPE_API_PRESENCE, presence, TRUE);
+    presence_string = _g_enum_to_string(MATRIX_TYPE_API_PRESENCE, presence, TRUE);
     json_builder_add_string_value(builder, presence_string);
     g_free(presence_string);
 
@@ -1416,7 +1416,7 @@ i_delete_pusher(MatrixAPI *api,
 
     encoded_scope = soup_uri_encode(scope, NULL);
     encoded_rule_id = soup_uri_encode(rule_id, NULL);
-    kind_string = g_enum_to_string(MATRIX_TYPE_API_PUSHER_KIND, kind, TRUE);
+    kind_string = _g_enum_to_string(MATRIX_TYPE_API_PUSHER_KIND, kind, TRUE);
 
     path = g_strdup_printf("pushrules/%s/%s/%s",
                            encoded_scope,
@@ -1448,7 +1448,7 @@ i_get_pusher(MatrixAPI *api,
 
     encoded_scope = soup_uri_encode(scope, NULL);
     encoded_rule_id = soup_uri_encode(rule_id, NULL);
-    kind_string = g_enum_to_string(MATRIX_TYPE_API_PUSHER_KIND, kind, TRUE);
+    kind_string = _g_enum_to_string(MATRIX_TYPE_API_PUSHER_KIND, kind, TRUE);
 
     path = g_strdup_printf("pushrules/%s/%s/%s",
                            encoded_scope,
@@ -1471,7 +1471,7 @@ static void
 add_condition_kind_object(MatrixAPIPusherConditionKind kind,
                           JsonBuilder *builder)
 {
-    gchar *kind_string = g_enum_to_string(
+    gchar *kind_string = _g_enum_to_string(
             MATRIX_TYPE_API_PUSHER_CONDITION_KIND, kind, TRUE);
 
     if (!kind_string) {
@@ -1507,7 +1507,7 @@ static void i_add_pusher(MatrixAPI *api,
 
     encoded_scope = soup_uri_encode(scope, NULL);
     encoded_rule_id = soup_uri_encode(rule_id, NULL);
-    kind_string = g_enum_to_string(MATRIX_TYPE_API_PUSHER_KIND, kind, TRUE);
+    kind_string = _g_enum_to_string(MATRIX_TYPE_API_PUSHER_KIND, kind, TRUE);
 
     path = g_strdup_printf("pushrules/%s/%s/%s",
                            encoded_scope,
@@ -1571,7 +1571,7 @@ i_toggle_pusher(MatrixAPI *api,
 
     encoded_scope = soup_uri_encode(scope, NULL);
     encoded_rule_id = soup_uri_encode(rule_id, NULL);
-    kind_string = g_enum_to_string(MATRIX_TYPE_API_PUSHER_KIND, kind, TRUE);
+    kind_string = _g_enum_to_string(MATRIX_TYPE_API_PUSHER_KIND, kind, TRUE);
 
     path = g_strdup_printf("pushrules/%s/%s/%s",
                            encoded_scope,
@@ -1955,7 +1955,7 @@ i_send_event_receipt(MatrixAPI *api,
 
     encoded_room_id = soup_uri_encode(room_id, NULL);
     encoded_event_id = soup_uri_encode(event_id, NULL);
-    receipt_type_string = g_enum_to_string(MATRIX_TYPE_API_RECEIPT_TYPE,
+    receipt_type_string = _g_enum_to_string(MATRIX_TYPE_API_RECEIPT_TYPE,
                                          receipt_type,
                                          TRUE);
     path = g_strdup_printf("rooms/%s/receipt/%s/%s",
@@ -2605,7 +2605,7 @@ i_register_account(MatrixAPI *api,
     g_object_unref(builder);
 
     if (account_kind != MATRIX_API_ACCOUNT_KIND_DEFAULT) {
-        gchar *kind_string = g_enum_to_string(MATRIX_TYPE_API_ACCOUNT_KIND,
+        gchar *kind_string = _g_enum_to_string(MATRIX_TYPE_API_ACCOUNT_KIND,
                                               account_kind, TRUE);
 
         params = create_query_params();
diff --git a/src/utils.c b/src/utils.c
index bf51e7e..15960c7 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -18,19 +18,8 @@
 
 #include "utils.h"
 
-/**
- * g_enum_to_string: (skip)
- * @type: a #GEnumType
- * @value: a value from @type
- * @convert_dashes: convert dashes to underscores
- *
- * Get the value nick for @value, optionally converting dashes to
- * underscores.
- *
- * Returns: (transfer full): :the value nick
- */
 gchar *
-g_enum_to_string(GType enum_type, gint value, gboolean convert_dashes)
+_g_enum_to_string(GType enum_type, gint value, gboolean convert_dashes)
 {
     GEnumClass *enum_class = g_type_class_ref(enum_type);
     GEnumValue *enum_value = g_enum_get_value(enum_class, value);
diff --git a/src/utils.h b/src/utils.h
index 8240bb2..487034d 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -22,6 +22,6 @@
 #include <glib.h>
 #include <glib-object.h>
 
-gchar *g_enum_to_string(GType enum_type, gint value, gboolean convert_dash);
+gchar *_g_enum_to_string(GType enum_type, gint value, gboolean convert_dash);
 
 #endif /* __MATRIX_UTILS_H__ */