Assert uri not null
diff --git a/src/core/client_config/resolver_registry.c b/src/core/client_config/resolver_registry.c
index af263df..886ca5d 100644
--- a/src/core/client_config/resolver_registry.c
+++ b/src/core/client_config/resolver_registry.c
@@ -90,6 +90,7 @@
   char *tmp;
   grpc_resolver_factory *factory = NULL;
 
+  GPR_ASSERT(uri);
   *uri = grpc_uri_parse(target, 1);
   factory = lookup_factory(*uri);
   if (factory == NULL) {