diff --git a/libavcodec/nellymoserdec.c b/libavcodec/nellymoserdec.c
index e1ec6e1fc0..37210cf42b 100644
--- a/libavcodec/nellymoserdec.c
+++ b/libavcodec/nellymoserdec.c
@@ -264,7 +264,9 @@ static void get_sample_bits(const float *buf, int *bits)
     }
 }
 
-void nelly_decode_block(NellyMoserDecodeContext *s, const unsigned char block[NELLY_BLOCK_LEN], float audio[NELLY_SAMPLES])
+static void nelly_decode_block(NellyMoserDecodeContext *s,
+                               const unsigned char block[NELLY_BLOCK_LEN],
+                               float audio[NELLY_SAMPLES])
 {
     int i,j;
     float buf[NELLY_FILL_LEN], pows[NELLY_FILL_LEN];