diff --git a/config.h b/config.h
index 2a7086c5f..cc9375a06 100644
--- a/config.h
+++ b/config.h
@@ -1,9 +1,14 @@
-/* Simple config.h for gcc. */
+/* Simple config.h for recent gcc. */
 #define HAVE_ALIGNOF 1
+#define HAVE_ATTRIBUTE_CONST 1
 #define HAVE_ATTRIBUTE_COLD 1
+#define HAVE_ATTRIBUTE_MAY_ALIAS 1
 #define HAVE_ATTRIBUTE_PRINTF 1
+#define HAVE_ATTRIBUTE_USED 1
+#define HAVE_ATTRIBUTE_UNUSED 1
 #define HAVE_BIG_ENDIAN 0
 #define HAVE_BUILTIN_CHOOSE_EXPR 1
+#define HAVE_BUILTIN_CONSTANT_P 1
 #define HAVE_BUILTIN_EXPECT 1
 #define HAVE_BUILTIN_TYPES_COMPATIBLE_P 1
 #define HAVE_GETPAGESIZE 1
@@ -13,9 +18,10 @@
 #define HAVE_STATEMENT_EXPR 1
 #define HAVE_TYPEOF 1
 #define HAVE_UTIME 1
+#define HAVE_BUILTIN_CLZ 1
 #define HAVE_BUILTIN_CLZL 1
+#define HAVE_BUILTIN_CLZLL 1
 #define HAVE_BUILTIN_FFSL 1
 #define HAVE_BUILTIN_POPCOUNTL 1
 #define HAVE_BYTESWAP_H 1
 #define HAVE_BSWAP_64 1
-#define HAVE_BUILTIN_CLZL 1