diff --git a/emhttp/plugins/dynamix.docker.manager/DockerSettings.page b/emhttp/plugins/dynamix.docker.manager/DockerSettings.page
index 190852c4f..4d09e61f9 100644
--- a/emhttp/plugins/dynamix.docker.manager/DockerSettings.page
+++ b/emhttp/plugins/dynamix.docker.manager/DockerSettings.page
@@ -320,8 +320,8 @@ _(IPv4 custom network on interface)_ <?=$network?> (_(optional)_):
 <?
   for ($b=$box; $b<=3; $b++) {
     switch ($b) {
-      case 1: $step = $size/65536%256; break;
-      case 2: $step = $size/256%256; break;
+      case 1: $step = floor($size/65536)%256; break;
+      case 2: $step = floor($size/256)%256; break;
       case 3: $step = $size%256; break;
     }
     if ($step===0) $step = 256;
@@ -781,8 +781,8 @@ function changeMask(id,val) {
   for (var b=1; b<=3; b++) {
     var cell = id+b;
     switch (b) {
-      case 1: var step = mask/65536%256; break;
-      case 2: var step = mask/256%256; break;
+      case 1: var step = floor(mask/65536)%256; break;
+      case 2: var step = floor(mask/256)%256; break;
       case 3: var step = mask%256; break;
     }
     if (step==0) step = 256;