diff --git a/libavcodec/agm.c b/libavcodec/agm.c
index a499c09082..2c4c9805e9 100644
--- a/libavcodec/agm.c
+++ b/libavcodec/agm.c
@@ -918,7 +918,7 @@ static void get_tree_codes(uint32_t *codes, Node *nodes, int idx, uint32_t pfx,
         codes[idx] = pfx;
     } else if (idx >= 0) {
         get_tree_codes(codes, nodes, nodes[idx].child[0], pfx + (0 << bitpos), bitpos + 1);
-        get_tree_codes(codes, nodes, nodes[idx].child[1], pfx + (1 << bitpos), bitpos + 1);
+        get_tree_codes(codes, nodes, nodes[idx].child[1], pfx + (1U << bitpos), bitpos + 1);
     }
 }