diff --git a/tftpd/tftpd.c b/tftpd/tftpd.c
index 364e7d2..e2659e0 100644
--- a/tftpd/tftpd.c
+++ b/tftpd/tftpd.c
@@ -1085,6 +1085,11 @@ int tftp(struct tftphdr *tp, int size)
 
     end = (char *)tp + size;
 
+    if (!*cp) {
+        nak(EBADOP, "Zero-length filename.");
+        exit(0);
+    }
+
     while (cp < end && *cp) {
         do {
             cp++;