diff --git a/src/hb-ot-shape.cc b/src/hb-ot-shape.cc
index ff92d5dfe..09c47c7de 100644
--- a/src/hb-ot-shape.cc
+++ b/src/hb-ot-shape.cc
@@ -900,9 +900,9 @@ hb_ot_substitute_post (const hb_ot_shape_context_t *c)
 #endif
 
   if (c->plan->shaper->postprocess_glyphs &&
-    c->buffer->message(c->font, "start postprocess")) {
+    c->buffer->message(c->font, "start postprocess-glyphs")) {
     c->plan->shaper->postprocess_glyphs (c->plan, c->buffer, c->font);
-    (void)c->buffer->message(c->font, "end postprocess");
+    (void)c->buffer->message(c->font, "end postprocess-glyphs");
   }
 }
 
@@ -1127,9 +1127,9 @@ hb_ot_shape_internal (hb_ot_shape_context_t *c)
   hb_ensure_native_direction (c->buffer);
 
   if (c->plan->shaper->preprocess_text &&
-    c->buffer->message(c->font, "start preprocess")) {
+    c->buffer->message(c->font, "start preprocess-text")) {
     c->plan->shaper->preprocess_text (c->plan, c->buffer, c->font);
-    (void)c->buffer->message(c->font, "end preprocess");
+    (void)c->buffer->message(c->font, "end preprocess-text");
   }
 
   hb_ot_substitute_pre (c);