diff --git a/sql/pgpool-recovery/pgpool-recovery.c b/sql/pgpool-recovery/pgpool-recovery.c
index 8408e3f..a981bf9 100644
--- a/sql/pgpool-recovery/pgpool-recovery.c
+++ b/sql/pgpool-recovery/pgpool-recovery.c
@@ -198,7 +198,14 @@ get_function_oid(const char *funcname, const char *argtype, const char *nspname)
 		oid_v = buildoidvector(NULL, 0);
 	}
 
+#if !defined(PG_VERSION_NUM) || (PG_VERSION_NUM < 90300)
 	nspid = LookupExplicitNamespace(nspname);
+#else
+	/* LookupExplicitNamespace() of PostgreSQL 9.3 or later, has third
+	 * argument "missing_ok" which suppresses ERROR exception, but
+	 * returns invlaid_oid. See include/catalog/namespace.h */
+	nspid = LookupExplicitNamespace(nspname, false);
+#endif
 	elog(DEBUG1, "get_function_oid: oid of \"%s\": %d", nspname, nspid);
 
 	tup = SearchSysCache(PROCNAMEARGSNSP,