diff --git a/include/maddy/blockparser.h b/include/maddy/blockparser.h
index 00bf5f3..c159825 100644
--- a/include/maddy/blockparser.h
+++ b/include/maddy/blockparser.h
@@ -7,6 +7,7 @@
 // -----------------------------------------------------------------------------
 
 #include <functional>
+#include <sstream>
 #include <string>
 
 // -----------------------------------------------------------------------------