diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
index ac39b3277b..ea586332b2 100644
--- a/libavcodec/pngdec.c
+++ b/libavcodec/pngdec.c
@@ -1095,7 +1095,7 @@ static int decode_sbit_chunk(AVCodecContext *avctx, PNGDecContext *s,
         bits = FFMAX(b, bits);
     }
 
-    if (bits < 0 || bits > s->bit_depth) {
+    if (bits <= 0 || bits > (s->color_type & PNG_COLOR_MASK_PALETTE ? 8 : s->bit_depth)) {
         av_log(avctx, AV_LOG_ERROR, "Invalid significant bits: %d\n", bits);
         return AVERROR_INVALIDDATA;
     }