diff --git a/lib/libc/iconv/_strtol.h b/lib/libc/iconv/_strtol.h
--- a/lib/libc/iconv/_strtol.h
+++ b/lib/libc/iconv/_strtol.h
@@ -83,7 +83,10 @@
 			c = *s++;
 	}
 	if ((base == 0 || base == 16) &&
-	    c == '0' && (*s == 'x' || *s == 'X')) {
+	    c == '0' && (*s == 'x' || *s == 'X') &&
+	    ((s[1] >= '0' && s[1] <= '9') ||
+	    (s[1] >= 'A' && s[1] <= 'F') ||
+	    (s[1] >= 'a' && s[1] <= 'f'))) {
 		c = s[1];
 		s += 2;
 		base = 16;
diff --git a/lib/libc/iconv/_strtoul.h b/lib/libc/iconv/_strtoul.h
--- a/lib/libc/iconv/_strtoul.h
+++ b/lib/libc/iconv/_strtoul.h
@@ -79,7 +79,10 @@
 			c = *s++;
 	}
 	if ((base == 0 || base == 16) &&
-	    c == '0' && (*s == 'x' || *s == 'X')) {
+	    c == '0' && (*s == 'x' || *s == 'X') &&
+	    ((s[1] >= '0' && s[1] <= '9') ||
+	    (s[1] >= 'A' && s[1] <= 'F') ||
+	    (s[1] >= 'a' && s[1] <= 'f'))) {
 		c = s[1];
 		s += 2;
 		base = 16;
diff --git a/lib/libc/locale/wcstoimax.c b/lib/libc/locale/wcstoimax.c
--- a/lib/libc/locale/wcstoimax.c
+++ b/lib/libc/locale/wcstoimax.c
@@ -78,7 +78,10 @@
 			c = *s++;
 	}
 	if ((base == 0 || base == 16) &&
-	    c == L'0' && (*s == L'x' || *s == L'X')) {
+	    c == L'0' && (*s == L'x' || *s == L'X') &&
+	    ((s[1] >= L'0' && s[1] <= L'9') ||
+	    (s[1] >= L'A' && s[1] <= L'F') ||
+	    (s[1] >= L'a' && s[1] <= L'f'))) {
 		c = s[1];
 		s += 2;
 		base = 16;
diff --git a/lib/libc/locale/wcstol.c b/lib/libc/locale/wcstol.c
--- a/lib/libc/locale/wcstol.c
+++ b/lib/libc/locale/wcstol.c
@@ -63,7 +63,7 @@
 	do {
 		c = *s++;
 	} while (iswspace_l(c, locale));
-	if (c == '-') {
+	if (c == L'-') {
 		neg = 1;
 		c = *s++;
 	} else {
@@ -72,7 +72,10 @@
 			c = *s++;
 	}
 	if ((base == 0 || base == 16) &&
-	    c == L'0' && (*s == L'x' || *s == L'X')) {
+	    c == L'0' && (*s == L'x' || *s == L'X') &&
+	    ((s[1] >= L'0' && s[1] <= L'9') ||
+	    (s[1] >= L'A' && s[1] <= L'F') ||
+	    (s[1] >= L'a' && s[1] <= L'f'))) {
 		c = s[1];
 		s += 2;
 		base = 16;
diff --git a/lib/libc/locale/wcstoll.c b/lib/libc/locale/wcstoll.c
--- a/lib/libc/locale/wcstoll.c
+++ b/lib/libc/locale/wcstoll.c
@@ -78,7 +78,10 @@
 			c = *s++;
 	}
 	if ((base == 0 || base == 16) &&
-	    c == L'0' && (*s == L'x' || *s == L'X')) {
+	    c == L'0' && (*s == L'x' || *s == L'X') &&
+	    ((s[1] >= L'0' && s[1] <= L'9') ||
+	    (s[1] >= L'A' && s[1] <= L'F') ||
+	    (s[1] >= L'a' && s[1] <= L'f'))) {
 		c = s[1];
 		s += 2;
 		base = 16;
diff --git a/lib/libc/locale/wcstoul.c b/lib/libc/locale/wcstoul.c
--- a/lib/libc/locale/wcstoul.c
+++ b/lib/libc/locale/wcstoul.c
@@ -72,7 +72,10 @@
 			c = *s++;
 	}
 	if ((base == 0 || base == 16) &&
-	    c == L'0' && (*s == L'x' || *s == L'X')) {
+	    c == L'0' && (*s == L'x' || *s == L'X') &&
+	    ((s[1] >= L'0' && s[1] <= L'9') ||
+	    (s[1] >= L'A' && s[1] <= L'F') ||
+	    (s[1] >= L'a' && s[1] <= L'f'))) {
 		c = s[1];
 		s += 2;
 		base = 16;
diff --git a/lib/libc/locale/wcstoull.c b/lib/libc/locale/wcstoull.c
--- a/lib/libc/locale/wcstoull.c
+++ b/lib/libc/locale/wcstoull.c
@@ -78,7 +78,10 @@
 			c = *s++;
 	}
 	if ((base == 0 || base == 16) &&
-	    c == L'0' && (*s == L'x' || *s == L'X')) {
+	    c == L'0' && (*s == L'x' || *s == L'X') &&
+	    ((s[1] >= L'0' && s[1] <= L'9') ||
+	    (s[1] >= L'A' && s[1] <= L'F') ||
+	    (s[1] >= L'a' && s[1] <= L'f'))) {
 		c = s[1];
 		s += 2;
 		base = 16;
diff --git a/lib/libc/locale/wcstoumax.c b/lib/libc/locale/wcstoumax.c
--- a/lib/libc/locale/wcstoumax.c
+++ b/lib/libc/locale/wcstoumax.c
@@ -78,7 +78,10 @@
 			c = *s++;
 	}
 	if ((base == 0 || base == 16) &&
-	    c == L'0' && (*s == L'x' || *s == L'X')) {
+	    c == L'0' && (*s == L'x' || *s == L'X') &&
+	    ((s[1] >= L'0' && s[1] <= L'9') ||
+	    (s[1] >= L'A' && s[1] <= L'F') ||
+	    (s[1] >= L'a' && s[1] <= L'f'))) {
 		c = s[1];
 		s += 2;
 		base = 16;