diff --git a/src/mesa/main/texenvprogram.c b/src/mesa/main/texenvprogram.c
index a70d069bd9c..b92ba2542d2 100644
--- a/src/mesa/main/texenvprogram.c
+++ b/src/mesa/main/texenvprogram.c
@@ -877,6 +877,7 @@ static struct ureg get_source( struct texenv_fragment_program *p,
 
    default:
       assert(0);
+      return undef;
    }
 }