diff --git a/src/http_conv.c b/src/http_conv.c
index a46432dc0..c0a2f9536 100644
--- a/src/http_conv.c
+++ b/src/http_conv.c
@@ -263,7 +263,7 @@ static int sample_conv_url_dec(const struct arg *args, struct sample *smp, void
 	  * before decoding.
 	 */
 	if (smp->flags & SMP_F_CONST || smp->data.u.str.size <= smp->data.u.str.data) {
-		struct buffer *str = get_trash_chunk_sz(smp->data.u.str.data);
+		struct buffer *str = get_trash_chunk_sz(smp->data.u.str.data + 1);
 
 		if (!str)
 			return 0;