diff --git a/src/glsl/ir.h b/src/glsl/ir.h
index fa246b5e570..e0347fbf32f 100644
--- a/src/glsl/ir.h
+++ b/src/glsl/ir.h
@@ -125,6 +125,7 @@ public:
    virtual class ir_if *                as_if()               { return NULL; }
    virtual class ir_swizzle *           as_swizzle()          { return NULL; }
    virtual class ir_constant *          as_constant()         { return NULL; }
+   virtual class ir_discard *           as_discard()          { return NULL; }
    /*@}*/
 
 protected:
@@ -1044,6 +1045,11 @@ public:
 
    virtual ir_visitor_status accept(ir_hierarchical_visitor *);
 
+   virtual ir_discard *as_discard()
+   {
+      return this;
+   }
+
    ir_rvalue *condition;
 };
 /*@}*/