diff --git a/pb.h b/pb.h
index fbdf185..b19dfcf 100644
--- a/pb.h
+++ b/pb.h
@@ -100,8 +100,8 @@ typedef enum {
     
     /* Works for all required/optional/repeated fields.
      * data_offset points to pb_callback_t structure.
-     * LTYPE should be 0 (it is ignored, but sometimes
-     * used to speculatively index an array). */
+     * LTYPE should be valid or 0 (it is ignored, but
+     * sometimes used to speculatively index an array). */
     PB_HTYPE_CALLBACK = 0x30,
     
     PB_HTYPE_MASK = 0xF0