diff --git a/build/lesshat-prefixed.less b/build/lesshat-prefixed.less
index 5d14e75..1581e22 100644
--- a/build/lesshat-prefixed.less
+++ b/build/lesshat-prefixed.less
@@ -2229,7 +2229,7 @@
 
 }
 
-.lh-size(@square:auto) {
+.lh-size(@square) {
   @unit: 'px';
   .process(@square) when (ispixel(@square)), (isem(@square)), (ispercentage(@square)), (iskeyword(@square)) {
     width: @square;
@@ -2245,7 +2245,7 @@
 
 }
 
-.lh-size(@width:auto, @height:auto) {
+.lh-size(@width, @height) {
   @unit: 'px';
   .process(@width, @height) when (ispixel(@width)) and (ispixel(@height)), (isem(@width)) and (isem(@height)), (ispercentage(@width)) and (ispercentage(@height)), (iskeyword(@width)) and (iskeyword(@height)) {
     width: @width;
diff --git a/build/lesshat.less b/build/lesshat.less
index 1e7b8c3..2056d64 100644
--- a/build/lesshat.less
+++ b/build/lesshat.less
@@ -2229,7 +2229,7 @@
 
 }
 
-.size(@square:auto) {
+.size(@square) {
   @unit: 'px';
   .process(@square) when (ispixel(@square)), (isem(@square)), (ispercentage(@square)), (iskeyword(@square)) {
     width: @square;
@@ -2245,7 +2245,7 @@
 
 }
 
-.size(@width:auto, @height:auto) {
+.size(@width, @height) {
   @unit: 'px';
   .process(@width, @height) when (ispixel(@width)) and (ispixel(@height)), (isem(@width)) and (isem(@height)), (ispercentage(@width)) and (ispercentage(@height)), (iskeyword(@width)) and (iskeyword(@height)) {
     width: @width;
diff --git a/mixins/size/size.less b/mixins/size/size.less
index 7d8d2c4..12dacd1 100644
--- a/mixins/size/size.less
+++ b/mixins/size/size.less
@@ -1,4 +1,4 @@
-.size(@square:auto) {
+.size(@square) {
   @unit: 'px';
   .process(@square) when (ispixel(@square)), (isem(@square)), (ispercentage(@square)), (iskeyword(@square)) {
     width: @square;
@@ -14,7 +14,7 @@
 
 }
 
-.size(@width:auto, @height:auto) {
+.size(@width, @height) {
   @unit: 'px';
   .process(@width, @height) when (ispixel(@width)) and (ispixel(@height)), (isem(@width)) and (isem(@height)), (ispercentage(@width)) and (ispercentage(@height)), (iskeyword(@width)) and (iskeyword(@height)) {
     width: @width;