diff --git a/libc/include/llvm-libc-types/size_t.h b/libc/include/llvm-libc-types/size_t.h
index 3b31b0820f237..26ae68abe0ee7 100644
--- a/libc/include/llvm-libc-types/size_t.h
+++ b/libc/include/llvm-libc-types/size_t.h
@@ -9,11 +9,6 @@
 #ifndef LLVM_LIBC_TYPES_SIZE_T_H
 #define LLVM_LIBC_TYPES_SIZE_T_H
 
-// Since __need_size_t is defined, we get the definition of size_t from the
-// standalone C header stddef.h. Also, because __need_size_t is defined,
-// including stddef.h will pull only the type size_t and nothing else.
-#define __need_size_t
-#include <stddef.h>
-#undef __need_size_t
+typedef __SIZE_TYPE__ size_t;
 
 #endif // LLVM_LIBC_TYPES_SIZE_T_H
diff --git a/libc/include/llvm-libc-types/ssize_t.h b/libc/include/llvm-libc-types/ssize_t.h
index 41e4b6d2c500a..8f579e2749bac 100644
--- a/libc/include/llvm-libc-types/ssize_t.h
+++ b/libc/include/llvm-libc-types/ssize_t.h
@@ -9,6 +9,6 @@
 #ifndef LLVM_LIBC_TYPES_SSIZE_T_H
 #define LLVM_LIBC_TYPES_SSIZE_T_H
 
-typedef __INT64_TYPE__ ssize_t;
+typedef __PTRDIFF_TYPE__ ssize_t;
 
 #endif // LLVM_LIBC_TYPES_SSIZE_T_H