diff --git a/src/glsl/link_varyings.cpp b/src/glsl/link_varyings.cpp
index 7cc58800765..3853abdb8e6 100644
--- a/src/glsl/link_varyings.cpp
+++ b/src/glsl/link_varyings.cpp
@@ -1295,12 +1295,13 @@ public:
 
    void process(ir_variable *var)
    {
-      /* All named varying interface blocks should be flattened by now */
-      assert(!var->is_interface_instance());
-
       this->toplevel_var = var;
       this->varying_floats = 0;
-      program_resource_visitor::process(var);
+      if (var->is_interface_instance())
+         program_resource_visitor::process(var->get_interface_type(),
+                                           var->get_interface_type()->name);
+      else
+         program_resource_visitor::process(var);
    }
 
 private: