diff --git a/headers/posix/stdint.h b/headers/posix/stdint.h
index ad26836f06..a96e933188 100644
--- a/headers/posix/stdint.h
+++ b/headers/posix/stdint.h
@@ -19,7 +19,33 @@ typedef signed long long int64_t;
 typedef unsigned long long uintmax_t;
 typedef signed long long intmax_t;
 
-// ToDo: add "least" and "fast" types
+// least types
+
+typedef uint8_t uint_least8_t;
+typedef int8_t int_least8_t;
+
+typedef uint16_t uint_least16_t;
+typedef int16_t int_least16_t;
+
+typedef uint32_t uint_least32_t;
+typedef int32_t int_least32_t;
+
+typedef uint64_t uint_least64_t;
+typedef int64_t int_least64_t;
+
+// fast types assume a 32-bit processor
+
+typedef uint32_t uint_fast8_t;
+typedef int32_t int_fast8_t;
+
+typedef uint32_t uint_fast16_t;
+typedef int32_t int_fast16_t;
+
+typedef uint32_t uint_fast32_t;
+typedef int32_t int_fast32_t;
+
+typedef uint64_t uint_fast64_t;
+typedef int64_t int_fast64_t;
 
 /* BSD compatibility */
 typedef uint8_t u_int8_t;