diff --git a/buffer.c b/buffer.c
index 08e4b6b3587688b8063f79460d81470fa5b6dda7..e61b471f61ec12975b898b99dbb254f1590c1225 100644
--- a/buffer.c
+++ b/buffer.c
@@ -33,7 +33,7 @@ int
 nettle_buffer_grow(struct nettle_buffer *buffer,
 		   unsigned length)
 {
-  assert(buffer->size <= buffer->realloc);
+  assert(buffer->size <= buffer->alloc);
   
   if (buffer->size + length > buffer->alloc)
     {