diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
index b0d02c97dd..cb861e5f60 100644
--- a/libavcodec/pngdec.c
+++ b/libavcodec/pngdec.c
@@ -1086,8 +1086,11 @@ static int decode_sbit_chunk(AVCodecContext *avctx, PNGDecContext *s,
 
     channels = s->color_type & PNG_COLOR_MASK_PALETTE ? 3 : ff_png_get_nb_channels(s->color_type);
 
-    if (bytestream2_get_bytes_left(gb) != channels)
+    if (bytestream2_get_bytes_left(gb) != channels) {
+        av_log(avctx, AV_LOG_ERROR, "Invalid sBIT size: %d, expected: %d\n",
+            bytestream2_get_bytes_left(gb), channels);
         return AVERROR_INVALIDDATA;
+    }
 
     for (int i = 0; i < channels; i++) {
         int b = bytestream2_get_byteu(gb);