diff --git a/src/interfaces/libpq/fe-exec.c b/src/interfaces/libpq/fe-exec.c
index 916eb45d4a8..41b2fcd9f5f 100644
--- a/src/interfaces/libpq/fe-exec.c
+++ b/src/interfaces/libpq/fe-exec.c
@@ -3221,6 +3221,8 @@ PQsetnonblocking(PGconn *conn, int arg)
 int
 PQisnonblocking(const PGconn *conn)
 {
+	if (!conn || conn->status == CONNECTION_BAD)
+		return false;
 	return pqIsnonblocking(conn);
 }
 
@@ -3240,6 +3242,8 @@ PQisthreadsafe(void)
 int
 PQflush(PGconn *conn)
 {
+	if (!conn || conn->status == CONNECTION_BAD)
+		return -1;
 	return pqFlush(conn);
 }