diff --git a/src/plugins/fts-solr/fts-solr-plugin.c b/src/plugins/fts-solr/fts-solr-plugin.c
index 19b89b1906..5f9e16cac3 100644
--- a/src/plugins/fts-solr/fts-solr-plugin.c
+++ b/src/plugins/fts-solr/fts-solr-plugin.c
@@ -34,7 +34,7 @@ fts_solr_plugin_init_settings(struct mail_user *user,
 			set->use_libfts = TRUE;
 		} else if (strcmp(*tmp, "break-imap-search") == 0) {
 			/* for backwards compatibility */
-		} else if (strcmp(*tmp, "default_ns=") == 0) {
+		} else if (str_begins(*tmp, "default_ns=")) {
 			set->default_ns_prefix =
 				p_strdup(user->pool, *tmp + 11);
 		} else {