diff --git a/libavcodec/bonk.c b/libavcodec/bonk.c
index 4a00270392..6ec7d3bb52 100644
--- a/libavcodec/bonk.c
+++ b/libavcodec/bonk.c
@@ -270,14 +270,14 @@ static inline int shift(int a, int b)
 
 static int predictor_calc_error(int *k, int *state, int order, int error)
 {
-    int i, x = error - shift_down(k[order-1] * state[order-1], LATTICE_SHIFT);
+    int i, x = error - shift_down(k[order-1] * (unsigned)state[order-1], LATTICE_SHIFT);
     int *k_ptr = &(k[order-2]),
         *state_ptr = &(state[order-2]);
 
     for (i = order-2; i >= 0; i--, k_ptr--, state_ptr--) {
         unsigned k_value = *k_ptr, state_value = *state_ptr;
 
-        x -= shift_down(k_value * state_value, LATTICE_SHIFT);
+        x -= shift_down(k_value * (unsigned)state_value, LATTICE_SHIFT);
         state_ptr[1] = state_value + shift_down(k_value * x, LATTICE_SHIFT);
     }