diff --git a/mpeg/psi.h b/mpeg/psi.h
index 8935671..6a4eb62 100644
--- a/mpeg/psi.h
+++ b/mpeg/psi.h
@@ -542,6 +542,7 @@ static inline uint8_t *psi_assemble_payload(uint8_t **pp_psi_buffer,
         if (i_section_size > PSI_PRIVATE_MAX_SIZE) {
             /* invalid section */
             psi_assemble_reset(pp_psi_buffer, pi_psi_buffer_used);
+            *pi_length = 0;
             return NULL;
         }
         if (i_section_size <= *pi_psi_buffer_used) {