diff --git a/config/test_quiet_include.h b/config/test_quiet_include.h
index f4fa4d30dd774aa90c6715c032e4f70500136ea4..732b23149e94684ae675c206f31673047366f15a 100644
--- a/config/test_quiet_include.h
+++ b/config/test_quiet_include.h
@@ -7,3 +7,12 @@ fun()
 {
 	return 0;
 }
+
+/*
+ * "IBM XL C/C++ for AIX, V12.1" miscompiles, for 32-bit, some inline
+ * expansions of ginCompareItemPointers() "long long" arithmetic.  To take
+ * advantage of inlining, build a 64-bit PostgreSQL.
+ */
+#if defined(__ILP32__) && defined(__IBMC__)
+#error "known inlining bug"
+#endif