diff --git a/src/interfaces/libpq/fe-cancel.c b/src/interfaces/libpq/fe-cancel.c
index 9562a7fe44..213a6f43c2 100644
--- a/src/interfaces/libpq/fe-cancel.c
+++ b/src/interfaces/libpq/fe-cancel.c
@@ -299,7 +299,8 @@ PQcancelSocket(const PGcancelConn *cancelConn)
 /*
  *		PQcancelErrorMessage
  *
- * Get the socket of the cancel connection.
+ * Returns the error message most recently generated by an operation on the
+ * cancel connection.
  */
 char *
 PQcancelErrorMessage(const PGcancelConn *cancelConn)