diff --git a/src/gallium/drivers/softpipe/sp_state.h b/src/gallium/drivers/softpipe/sp_state.h
index 4914b11cba8..63f6994bbc4 100644
--- a/src/gallium/drivers/softpipe/sp_state.h
+++ b/src/gallium/drivers/softpipe/sp_state.h
@@ -64,6 +64,8 @@ struct vertex_info;
 
 struct sp_fragment_shader_variant_key
 {
+   /* Standard C doesn't allow 0-size structs */
+   int dummy;
 };