diff --git a/lib/libc/minimal/include/bits/null.h b/lib/libc/minimal/include/bits/null.h
deleted file mode 100644
index 55d65ff7044..00000000000
--- a/lib/libc/minimal/include/bits/null.h
+++ /dev/null
@@ -1,28 +0,0 @@
-/*
- * Copyright (c) 2016 Wind River Systems, Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-/**
- * @file
- * @brief NULL definition
- */
-
-#if !defined(NULL)
-#ifdef __cplusplus
-	#define NULL 0
-#else
-	#define NULL (void *)0
-#endif
-#endif
diff --git a/lib/libc/minimal/include/bits/size_t.h b/lib/libc/minimal/include/bits/size_t.h
deleted file mode 100644
index 0ac252588b8..00000000000
--- a/lib/libc/minimal/include/bits/size_t.h
+++ /dev/null
@@ -1,37 +0,0 @@
-/*
- * Copyright (c) 2016 Wind River Systems, Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-/**
- * @file
- * @brief size_t definition
- */
-
-#if !defined(__size_t_defined)
-#define __size_t_defined
-
-#ifdef __i386
-typedef unsigned long int size_t;
-#elif defined(__ARM_ARCH)
-typedef unsigned int size_t;
-#elif defined(__arc__)
-typedef unsigned int size_t;
-#elif defined(__NIOS2__)
-typedef unsigned int size_t;
-#else
-#error "The minimal libc library does not recognize the architecture!\n"
-#endif
-
-#endif
diff --git a/lib/libc/minimal/include/stdio.h b/lib/libc/minimal/include/stdio.h
index 5cf10b6986a..48f78db6d77 100644
--- a/lib/libc/minimal/include/stdio.h
+++ b/lib/libc/minimal/include/stdio.h
@@ -20,9 +20,8 @@
 #define __INC_stdio_h__
 
 #include <stdarg.h>     /* Needed to get definition of va_list */
-#include <bits/null.h>
-#include <bits/size_t.h>
 #include <bits/restrict.h>
+#include <stddef.h>
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/lib/libc/minimal/include/stdlib.h b/lib/libc/minimal/include/stdlib.h
index 43932053ac5..4657258429b 100644
--- a/lib/libc/minimal/include/stdlib.h
+++ b/lib/libc/minimal/include/stdlib.h
@@ -19,9 +19,7 @@
 #ifndef __INC_stdlib_h__
 #define __INC_stdlib_h__
 
-#include <bits/null.h>
-#include <bits/size_t.h>
-
+#include <stddef.h>
 #ifdef __cplusplus
 extern "C" {
 #endif
diff --git a/lib/libc/minimal/include/string.h b/lib/libc/minimal/include/string.h
index 8e98dd4c255..0b97c0fe39c 100644
--- a/lib/libc/minimal/include/string.h
+++ b/lib/libc/minimal/include/string.h
@@ -19,8 +19,7 @@
 #ifndef __INC_string_h__
 #define __INC_string_h__
 
-#include <bits/null.h>
-#include <bits/size_t.h>
+#include <stddef.h>
 #include <bits/restrict.h>
 
 #ifdef __cplusplus