diff --git a/src/hpack-enc.c b/src/hpack-enc.c
index c4c8ea240..836584ab4 100644
--- a/src/hpack-enc.c
+++ b/src/hpack-enc.c
@@ -109,7 +109,7 @@ int hpack_encode_header(struct buffer *out, const struct ist n,
 		out->area[len++] = 0x58; // literal with indexing -- name="cache-control" (idx 24)
 	else if (isteq(n, ist("content-length")))
 		out->area[len++] = 0x5c; // literal with indexing -- name="content-length" (idx 28)
-	else if (len_to_bytes(n.len) && len + len_to_bytes(n.len) + n.len <= size) {
+	else if (len_to_bytes(n.len) && len + 1 + len_to_bytes(n.len) + n.len <= size) {
 		out->area[len++] = 0x00;      /* literal without indexing -- new name */
 
 		len = hpack_encode_len(out->area, len, n.len);