diff --git a/src/matrix-c-compacts.c b/src/matrix-c-compacts.c
index 5d89882..476e8c4 100644
--- a/src/matrix-c-compacts.c
+++ b/src/matrix-c-compacts.c
@@ -1049,7 +1049,7 @@ matrix_filter_get_json_node(MatrixJsonCompact *matrix_json_compact, GError **err
     json_builder_end_array(builder);
 
     json_builder_set_member_name(builder, "event_format");
-    json_builder_add_string_value(builder, _matrix_g_enum_to_string(MATRIX_TYPE_EVENT_FORMAT, priv->_event_format, TRUE));
+    json_builder_add_string_value(builder, _matrix_g_enum_to_string(MATRIX_TYPE_EVENT_FORMAT, priv->_event_format, '_'));
 
     json_builder_set_member_name(builder, "presence");
     node = matrix_json_compact_get_json_node(MATRIX_JSON_COMPACT(priv->_presence_filter), &inner_error);
@@ -2231,7 +2231,7 @@ matrix_search_grouping_get_json_node(MatrixJsonCompact *matrix_json_compact, GEr
 
 
     json_builder_set_member_name(builder, "key");
-    json_builder_add_string_value(builder, _matrix_g_enum_to_string(MATRIX_TYPE_SEARCH_GROUP_BY, priv->_key, TRUE));
+    json_builder_add_string_value(builder, _matrix_g_enum_to_string(MATRIX_TYPE_SEARCH_GROUP_BY, priv->_key, '_'));
 
     json_builder_end_object(builder);
 
diff --git a/src/utils.c b/src/utils.c
index 5c4f8da..822f0cd 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -35,7 +35,7 @@
  * Returns: (transfer full) the converted enum name, which must be freed
  */
 gchar *
-_matrix_g_enum_to_string(GType enum_type, gint value, gboolean convert_dashes)
+_matrix_g_enum_to_string(GType enum_type, gint value, gchar convert_dashes)
 {
     GEnumClass *enum_class = g_type_class_ref(enum_type);
     GEnumValue *enum_value = g_enum_get_value(enum_class, value);
@@ -49,7 +49,7 @@ _matrix_g_enum_to_string(GType enum_type, gint value, gboolean convert_dashes)
 
             for (a = nick; *a; a++) {
                 if (*a == '-') {
-                    *a = '_';
+                    *a = convert_dashes;
                 }
             }
         }
diff --git a/src/utils.h b/src/utils.h
index a5a14c5..ab432a1 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -23,7 +23,7 @@
 
 G_BEGIN_DECLS
 
-gchar *_matrix_g_enum_to_string(GType enum_type, gint value, gboolean convert_dashes);
+gchar *_matrix_g_enum_to_string(GType enum_type, gint value, gchar convert_dashes);
 gint _matrix_g_enum_nick_to_value(GType enum_type, const gchar *nick, GError **error);
 
 G_END_DECLS
diff --git a/vapi/c-api.vapi b/vapi/c-api.vapi
index 61b81e5..ba2fc44 100644
--- a/vapi/c-api.vapi
+++ b/vapi/c-api.vapi
@@ -384,7 +384,7 @@ namespace Matrix {
 
     /* Utilities */
     [CCode (cheader_filename = "utils.h", cname = "_matrix_g_enum_to_string")]
-    public string? _g_enum_value_to_nick(GLib.Type enum_type, int value, bool convert_dashes = true);
+    public string? _g_enum_value_to_nick(GLib.Type enum_type, int value, char convert_dashes = '_');
 
     [CCode (cheader_filename = "utils.h", cname = "_matrix_g_enum_nick_to_value")]
     public int _g_enum_nick_to_value(GLib.Type enum_type, string nick)