diff --git a/libavcodec/iff.c b/libavcodec/iff.c
index 500f9bf367..0656ae5509 100644
--- a/libavcodec/iff.c
+++ b/libavcodec/iff.c
@@ -456,11 +456,12 @@ static av_cold int decode_init(AVCodecContext *avctx)
  */
 static void decodeplane8(uint8_t *dst, const uint8_t *buf, int buf_size, int plane)
 {
-    const uint64_t *lut = plane8_lut[plane];
+    const uint64_t *lut;
     if (plane >= 8) {
         av_log(NULL, AV_LOG_WARNING, "Ignoring extra planes beyond 8\n");
         return;
     }
+    lut = plane8_lut[plane];
     do {
         uint64_t v = AV_RN64A(dst) | lut[*buf++];
         AV_WN64A(dst, v);