diff --git a/decoder/ihevcd_parse_slice_header.c b/decoder/ihevcd_parse_slice_header.c
index c161fc4..46f2f5f 100644
--- a/decoder/ihevcd_parse_slice_header.c
+++ b/decoder/ihevcd_parse_slice_header.c
@@ -471,7 +471,8 @@
                     ps_slice_hdr->i1_num_long_term_sps = value;
                 }
                 UEV_PARSE("num_long_term_pics", value, ps_bitstrm);
-                if((value + ps_slice_hdr->i1_num_long_term_sps + num_neg_pics + num_pos_pics) > (MAX_DPB_SIZE - 1))
+                if(((ULWORD64)value + ps_slice_hdr->i1_num_long_term_sps + num_neg_pics +
+                    num_pos_pics) > (MAX_DPB_SIZE - 1))
                 {
                     return IHEVCD_INVALID_PARAMETER;
                 }
@@ -487,6 +488,10 @@
                         {
                             WORD32 num_bits = 32 - CLZ(ps_sps->i1_num_long_term_ref_pics_sps - 1);
                             BITS_PARSE("lt_idx_sps[ i ]", value, ps_bitstrm, num_bits);
+                            if(value >= ps_sps->i1_num_long_term_ref_pics_sps)
+                            {
+                                return IHEVCD_INVALID_PARAMETER;
+                            }
                         }
                         else
                         {