diff --git a/libtcc.c b/libtcc.c
index c25fb2c..8e43fe2 100644
--- a/libtcc.c
+++ b/libtcc.c
@@ -1892,8 +1892,8 @@ TCCState *tcc_new(void)
     tcc_define_symbol(s, "__TINYC__", NULL);
 
     /* tiny C & gcc defines */
-    tcc_define_symbol(s, "__SIZE_TYPE__", "unsigned int");
-    tcc_define_symbol(s, "__PTRDIFF_TYPE__", "int");
+    tcc_define_symbol(s, "__SIZE_TYPE__", "unsigned long");
+    tcc_define_symbol(s, "__PTRDIFF_TYPE__", "long");
 #ifdef TCC_TARGET_PE
     tcc_define_symbol(s, "__WCHAR_TYPE__", "unsigned short");
 #else
diff --git a/tests/tcctest.c b/tests/tcctest.c
index a2d481a..536f5aa 100644
--- a/tests/tcctest.c
+++ b/tests/tcctest.c
@@ -592,6 +592,8 @@ void array_test(int a[4])
         printf(" %3d", ((int *)tab2)[i]);
     }
     printf("\n");
+    printf("sizeof(size_t)=%d\n", sizeof(size_t));
+    printf("sizeof(ptrdiff_t)=%d\n", sizeof(ptrdiff_t));
 }
 
 void expr_test()