--- xnu/xnu-792.10.96/iokit/Kernel/IOStringFuncs.c
+++ xnu/xnu-201.5/iokit/Kernel/IOStringFuncs.c
@@ -71,6 +71,7 @@
 #include <limits.h>
 */
 #include <sys/types.h>
+#include <stddef.h>
 #include <machine/limits.h>
 
 typedef int BOOL;
@@ -357,10 +358,11 @@
  * Ignores `locale' stuff.  Assumes that the upper and lower case
  * alphabets and digits are each contiguous.
  */
-uint64_t
-strtouq(const char *nptr,
-	char **endptr,
-	register int base)
+u_quad_t
+strtouq(nptr, endptr, base)
+	const char *nptr;
+	char **endptr;
+	register int base;
 {
 	register const char *s = nptr;
 	register u_quad_t acc;