diff --git a/src/vector.c b/src/vector.c
index eaefc44..abab44e 100644
--- a/src/vector.c
+++ b/src/vector.c
@@ -437,6 +437,7 @@ vector_send(PG_FUNCTION_ARGS)
 
 /*
  * Convert vector to vector
+ * This is needed to check the type modifier
  */
 PGDLLEXPORT PG_FUNCTION_INFO_V1(vector);
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