diff --git a/src/collocatordb.h b/src/collocatordb.h
index 7803cd1..8bb3402 100644
--- a/src/collocatordb.h
+++ b/src/collocatordb.h
@@ -130,5 +130,6 @@
 extern void read_vocab(COLLOCATORDB *db, char *fname);
 extern char *get_version();
 extern uint64_t get_word_id(COLLOCATORDB *db, const char *word);
+extern uint64_t get_corpus_size(COLLOCATORDB *db);
 
 #endif