diff --git a/libavcodec/bonk.c b/libavcodec/bonk.c
index 409694f710..c3ad80ec73 100644
--- a/libavcodec/bonk.c
+++ b/libavcodec/bonk.c
@@ -273,7 +273,7 @@ static int predictor_calc_error(int *k, int *state, int order, int error)
         *state_ptr = &(state[order-2]);
 
     for (i = order-2; i >= 0; i--, k_ptr--, state_ptr--) {
-        int k_value = *k_ptr, state_value = *state_ptr;
+        unsigned k_value = *k_ptr, state_value = *state_ptr;
 
         x -= shift_down(k_value * state_value, LATTICE_SHIFT);
         state_ptr[1] = state_value + shift_down(k_value * x, LATTICE_SHIFT);