diff --git a/src/unistd/getcwd.c b/src/unistd/getcwd.c
index 2e540cd41daef91efd37c7656f8f9274d4447ed6..a7b925d2dbee5a99f5ec61b77b5870ae3a839143 100644
--- a/src/unistd/getcwd.c
+++ b/src/unistd/getcwd.c
@@ -7,7 +7,13 @@
 char *getcwd(char *buf, size_t size)
 {
 	char tmp[PATH_MAX];
-	if (!buf) buf = tmp, size = PATH_MAX;
+	if (!buf) {
+		buf = tmp;
+		size = PATH_MAX;
+	} else if (!size) {
+		errno = EINVAL;
+		return 0;
+	}
 	if (syscall(SYS_getcwd, buf, size) < 0) return 0;
 	return buf == tmp ? strdup(buf) : buf;
 }