diff --git a/src/collocatordb.h b/src/collocatordb.h
index 74f2f0e..adf764d 100644
--- a/src/collocatordb.h
+++ b/src/collocatordb.h
@@ -120,6 +120,7 @@
 
 extern COLLOCATORDB *open_collocatordb(const char *s);
 extern COLLOCATORDB *open_collocatordb_for_write(const char *s);
+extern void close_collocatordb(COLLOCATORDB *db);
 extern void inc_collocator(COLLOCATORDB *db, uint64_t w1, uint64_t w2, int8_t dist);
 extern void dump_collocators(COLLOCATORDB *db, uint32_t w1, uint32_t w2, int8_t dist);
 extern COLLOCATOR *get_collocators(COLLOCATORDB *db, uint32_t w1);