diff --git a/swig/libcorpussentence.i b/swig/libcorpussentence.i
index d580b81377394a74bc94a4e777b27d3158fea296..be08a46d7a9a32f0d8b04fa1f40c7d519e6601a4 100644
--- a/swig/libcorpussentence.i
+++ b/swig/libcorpussentence.i
@@ -47,6 +47,7 @@ namespace Corpus2 {
 }
 
 using namespace std;
+using namespace boost;
 using namespace Corpus2;
 
 #endif /* SWIG_LIBCORPUS2_SENTENCE_I */