diff --git a/sw/airborne/modules/computer_vision/opticflow/size_divergence.c b/sw/airborne/modules/computer_vision/opticflow/size_divergence.c
index b825e590de..197fa027a8 100644
--- a/sw/airborne/modules/computer_vision/opticflow/size_divergence.c
+++ b/sw/airborne/modules/computer_vision/opticflow/size_divergence.c
@@ -67,13 +67,13 @@ float get_size_divergence(struct flow_t *vectors, int count, int n_samples)
     for (i = 0; i < count; i++) {
       for (j = i + 1; j < count; j++) {
         // distance in previous image:
-        dx = vectors[i].pos.x - vectors[j].pos.x;
-        dy = vectors[i].pos.y - vectors[j].pos.y;
+        dx = (float)vectors[i].pos.x - (float)vectors[j].pos.x;
+        dy = (float)vectors[i].pos.y - (float)vectors[j].pos.y;
         distance_1 = sqrt(dx * dx + dy * dy);
 
         // distance in current image:
-        dx = vectors[i].pos.x + vectors[i].flow_x - vectors[j].pos.x - vectors[j].flow_x;
-        dy = vectors[i].pos.y + vectors[i].flow_y - vectors[j].pos.y - vectors[j].flow_y;
+        dx = (float)vectors[i].pos.x + (float)vectors[i].flow_x - (float)vectors[j].pos.x - (float)vectors[j].flow_x;
+        dy = (float)vectors[i].pos.y + (float)vectors[i].flow_y - (float)vectors[j].pos.y - (float)vectors[j].flow_y;
         distance_2 = sqrt(dx * dx + dy * dy);
 
         // calculate divergence for this sample:
@@ -102,13 +102,13 @@ float get_size_divergence(struct flow_t *vectors, int count, int n_samples)
       }
 
       // distance in previous image:
-      dx = vectors[i].pos.x - vectors[j].pos.x;
-      dy = vectors[i].pos.y - vectors[j].pos.y;
+      dx = (float)vectors[i].pos.x - (float)vectors[j].pos.x;
+      dy = (float)vectors[i].pos.y - (float)vectors[j].pos.y;
       distance_1 = sqrt(dx * dx + dy * dy);
 
       // distance in current image:
-      dx = vectors[i].pos.x + vectors[i].flow_x - vectors[j].pos.x - vectors[j].flow_x;
-      dy = vectors[i].pos.y + vectors[i].flow_y - vectors[j].pos.y - vectors[j].flow_y;
+      dx = (float)vectors[i].pos.x + (float)vectors[i].flow_x - (float)vectors[j].pos.x - (float)vectors[j].flow_x;
+      dy = (float)vectors[i].pos.y + (float)vectors[i].flow_y - (float)vectors[j].pos.y - (float)vectors[j].flow_y;
       distance_2 = sqrt(dx * dx + dy * dy);
 
       // calculate divergence for this sample: