diff --git a/libavcodec/alsdec.c b/libavcodec/alsdec.c
index 8a8bff1..0a6be7b 100644
--- a/libavcodec/alsdec.c
+++ b/libavcodec/alsdec.c
@@ -1290,8 +1290,16 @@
 
             if (ch[dep].time_diff_sign) {
                 t      = -t;
+                if (t > 0 && begin < t) {
+                    av_log(ctx->avctx, AV_LOG_ERROR, "begin %u smaller than time diff index %d.\n", begin, t);
+                    return AVERROR_INVALIDDATA;
+                }
                 begin -= t;
             } else {
+                if (t > 0 && end < t) {
+                    av_log(ctx->avctx, AV_LOG_ERROR, "end %u smaller than time diff index %d.\n", end, t);
+                    return AVERROR_INVALIDDATA;
+                }
                 end   -= t;
             }