Index: head/contrib/netbsd-tests/lib/libc/stdio/t_printf.c
===================================================================
--- head/contrib/netbsd-tests/lib/libc/stdio/t_printf.c
+++ head/contrib/netbsd-tests/lib/libc/stdio/t_printf.c
@@ -120,12 +120,6 @@
 {
 	char s[16], fmt[32];
 
-#ifndef __NetBSD__
-	atf_tc_expect_signal(SIGSEGV,
-	    "some non-NetBSD platforms including FreeBSD don't validate "
-	    "negative size; testcase blows up with SIGSEGV");
-#endif
-
 	snprintf(fmt, sizeof(fmt), "%%%zu$d", SIZE_MAX / sizeof(size_t));
 
 	ATF_CHECK(snprintf(s, sizeof(s), fmt, -23) == -1);
Index: head/include/limits.h
===================================================================
--- head/include/limits.h
+++ head/include/limits.h
@@ -120,7 +120,7 @@
 #endif
 
 #if __XSI_VISIBLE || __POSIX_VISIBLE >= 200809
-#define	NL_ARGMAX		99	/* max # of position args for printf */
+#define	NL_ARGMAX		65536	/* max # of position args for printf */
 #define	NL_MSGMAX		32767
 #define	NL_SETMAX		255
 #define	NL_TEXTMAX		2048
Index: head/lib/libc/stdio/printf-pos.c
===================================================================
--- head/lib/libc/stdio/printf-pos.c
+++ head/lib/libc/stdio/printf-pos.c
@@ -44,6 +44,7 @@
 #include "namespace.h"
 #include <sys/types.h>
 
+#include <limits.h>
 #include <stdarg.h>
 #include <stddef.h>
 #include <stdint.h>
@@ -55,6 +56,12 @@
 #include "un-namespace.h"
 #include "printflocal.h"
 
+#ifdef	NL_ARGMAX
+#define	MAX_POSARG	NL_ARGMAX
+#else
+#define	MAX_POSARG	65536
+#endif
+
 /*
  * Type ids for argument type table.
  */
@@ -70,9 +77,9 @@
 struct typetable {
 	enum typeid *table; /* table of types */
 	enum typeid stattable[STATIC_ARG_TBL_SIZE];
-	int tablesize;		/* current size of type table */
-	int tablemax;		/* largest used index in table */
-	int nextarg;		/* 1-based argument index */
+	u_int tablesize;	/* current size of type table */
+	u_int tablemax;		/* largest used index in table */
+	u_int nextarg;		/* 1-based argument index */
 };
 
 static int	__grow_type_table(struct typetable *);
@@ -84,7 +91,7 @@
 static inline void
 inittypes(struct typetable *types)
 {
-	int n;
+	u_int n;
 
 	types->table = types->stattable;
 	types->tablesize = STATIC_ARG_TBL_SIZE;
@@ -185,7 +192,7 @@
 addaster(struct typetable *types, char **fmtp)
 {
 	char *cp;
-	int n2;
+	u_int n2;
 
 	n2 = 0;
 	cp = *fmtp;
@@ -194,7 +201,7 @@
 		cp++;
 	}
 	if (*cp == '$') {
-		int hold = types->nextarg;
+		u_int hold = types->nextarg;
 		types->nextarg = n2;
 		if (addtype(types, T_INT))
 			return (-1);
@@ -211,7 +218,7 @@
 addwaster(struct typetable *types, wchar_t **fmtp)
 {
 	wchar_t *cp;
-	int n2;
+	u_int n2;
 
 	n2 = 0;
 	cp = *fmtp;
@@ -220,7 +227,7 @@
 		cp++;
 	}
 	if (*cp == '$') {
-		int hold = types->nextarg;
+		u_int hold = types->nextarg;
 		types->nextarg = n2;
 		if (addtype(types, T_INT))
 			return (-1);
@@ -245,7 +252,7 @@
 {
 	char *fmt;		/* format string */
 	int ch;			/* character from fmt */
-	int n;			/* handy integer (short term usage) */
+	u_int n;		/* handy integer (short term usage) */
 	int error;
 	int flags;		/* flags as above */
 	struct typetable types;	/* table of types */
@@ -296,6 +303,11 @@
 			n = 0;
 			do {
 				n = 10 * n + to_digit(ch);
+				/* Detect overflow */
+				if (n > MAX_POSARG) {
+					error = -1;
+					goto error;
+				}
 				ch = *fmt++;
 			} while (is_digit(ch));
 			if (ch == '$') {
@@ -433,7 +445,7 @@
 {
 	wchar_t *fmt;		/* format string */
 	wchar_t ch;		/* character from fmt */
-	int n;			/* handy integer (short term usage) */
+	u_int n;		/* handy integer (short term usage) */
 	int error;
 	int flags;		/* flags as above */
 	struct typetable types;	/* table of types */
@@ -484,6 +496,11 @@
 			n = 0;
 			do {
 				n = 10 * n + to_digit(ch);
+				/* Detect overflow */
+				if (n > MAX_POSARG) {
+					error = -1;
+					goto error;
+				}
 				ch = *fmt++;
 			} while (is_digit(ch));
 			if (ch == '$') {
@@ -624,7 +641,11 @@
 	enum typeid *const oldtable = types->table;
 	const int oldsize = types->tablesize;
 	enum typeid *newtable;
-	int n, newsize = oldsize * 2;
+	u_int n, newsize = oldsize * 2;
+
+	/* Detect overflow */
+	if (types->nextarg > NL_ARGMAX)
+		return (-1);
 
 	if (newsize < types->nextarg + 1)
 		newsize = types->nextarg + 1;
@@ -653,7 +674,7 @@
 static void
 build_arg_table(struct typetable *types, va_list ap, union arg **argtable)
 {
-	int n;
+	u_int n;
 
 	if (types->tablemax >= STATIC_ARG_TBL_SIZE) {
 		*argtable = (union arg *)