diff --git commerce_vat.module commerce_vat.module
index eec3593..9bc9d6c 100644
--- commerce_vat.module
+++ commerce_vat.module
@@ -343,9 +343,14 @@ function commerce_vat_rate_apply($vat_rate, $line_item) {
          if ($component['price']['amount']) {
            $nonzero_components[] = &$component;
          }
-         $amount_to_reduce_current = commerce_vat_rate_round_amount($component['price']['amount'] / $amount * $amount_to_reduce_total);
-         $component['price']['amount'] -= $amount_to_reduce_current;
-         $amount_to_reduce_left -= $amount_to_reduce_current;
+
+         $division = $amount * $amount_to_reduce_total;
+         // Avoid division-by-zero warning from PHP
+         if ($division > 0) {
+           $amount_to_reduce_current = commerce_vat_rate_round_amount($component['price']['amount'] / $division);
+           $component['price']['amount'] -= $amount_to_reduce_current;
+           $amount_to_reduce_left -= $amount_to_reduce_current
+         }
        }
        // Change components only if there was a nonzero-one.
        if (!empty($nonzero_components)) {