diff --git a/libtcc.c b/libtcc.c
index d63b86f..b0fcdf9 100644
--- a/libtcc.c
+++ b/libtcc.c
@@ -1146,9 +1146,11 @@ LIBTCCAPI TCCState *tcc_new(void)
 #if defined TCC_TARGET_PE && defined TCC_TARGET_X86_64
     tcc_define_symbol(s, "__SIZE_TYPE__", "unsigned long long");
     tcc_define_symbol(s, "__PTRDIFF_TYPE__", "long long");
+    tcc_define_symbol(s, "__LLP64__", NULL);
 #else
     tcc_define_symbol(s, "__SIZE_TYPE__", "unsigned long");
     tcc_define_symbol(s, "__PTRDIFF_TYPE__", "long");
+    tcc_define_symbol(s, "__LP64__", NULL);
 #endif
 
 #ifdef TCC_TARGET_PE