diff --git a/src/hb-buffer.cc b/src/hb-buffer.cc
index 596d38c3b..11639efce 100644
--- a/src/hb-buffer.cc
+++ b/src/hb-buffer.cc
@@ -255,7 +255,7 @@ hb_buffer_reset (hb_buffer_t *buffer)
 }
 
 hb_bool_t
-hb_buffer_ensure (hb_buffer_t *buffer, unsigned int size)
+hb_buffer_pre_allocate (hb_buffer_t *buffer, unsigned int size)
 {
   return _hb_buffer_ensure (buffer, size);
 }
@@ -453,7 +453,7 @@ hb_bool_t
 hb_buffer_set_length (hb_buffer_t  *buffer,
 		      unsigned int  length)
 {
-  if (!hb_buffer_ensure (buffer, length))
+  if (!_hb_buffer_ensure (buffer, length))
     return FALSE;
 
   /* Wipe the new space */
diff --git a/src/hb-buffer.h b/src/hb-buffer.h
index 3c0a442fd..0c3ef3a31 100644
--- a/src/hb-buffer.h
+++ b/src/hb-buffer.h
@@ -107,8 +107,8 @@ void
 hb_buffer_reset (hb_buffer_t *buffer);
 
 hb_bool_t
-hb_buffer_ensure (hb_buffer_t  *buffer,
-		  unsigned int  size);
+hb_buffer_pre_allocate (hb_buffer_t  *buffer,
+		        unsigned int  size);
 
 void
 hb_buffer_reverse (hb_buffer_t *buffer);