diff --git a/headers/posix/assert.h b/headers/posix/assert.h
index d916e02e60..628cd4c843 100644
--- a/headers/posix/assert.h
+++ b/headers/posix/assert.h
@@ -3,19 +3,19 @@
  * Distributed under the terms of the MIT License.
  */
 
-/* Include guards are omitted, as assert.h is required
+/* Include guards are only on part of the file, as assert.h is required
    to support being included multiple times.
-   
+
    E.g. the following is required to be valid:
-   
+
    #undef NDEBUG
    #include <assert.h>
-   
+
    assert(0); // this assertion will be triggered
-   
+
    #define NDEBUG
    #include <assert.h>
-   
+
    assert(0); // this assertion will not be triggered
 */
 
@@ -24,6 +24,9 @@
 #ifndef NDEBUG
 	/* defining NDEBUG disables assert() functionality */
 
+#ifndef _ASSERT_H_
+#define _ASSERT_H_
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -40,6 +43,8 @@ extern void __assert_perror_fail(int error, const char *file,
 }
 #endif
 
+#endif /* !_ASSERT_H_ */
+
 #define assert(assertion) \
 	((assertion) ? (void)0 : __assert_fail(#assertion, __FILE__, __LINE__, __PRETTY_FUNCTION__))