diff --git a/src/encoding/block.cpp b/src/encoding/block.cpp
index e6a8b80..9c8ba1e 100644
--- a/src/encoding/block.cpp
+++ b/src/encoding/block.cpp
@@ -183,7 +183,7 @@
 }
 
 void
-Block::parse()
+Block::parse() const
 {
   if (!m_subBlocks.empty() || value_size()==0)
     return;