diff --git a/libavcodec/alsdec.c b/libavcodec/alsdec.c
index e54440910c..420bcf835a 100644
--- a/libavcodec/alsdec.c
+++ b/libavcodec/alsdec.c
@@ -1033,7 +1033,7 @@ static int decode_block(ALSDecContext *ctx, ALSBlockData *bd)
 
     if (*bd->shift_lsbs)
         for (smp = 0; smp < bd->block_length; smp++)
-            bd->raw_samples[smp] <<= *bd->shift_lsbs;
+            bd->raw_samples[smp] = (unsigned)bd->raw_samples[smp] << *bd->shift_lsbs;
 
     return 0;
 }