diff --git a/assets/stylesheets/addons/_position.scss b/assets/stylesheets/addons/_position.scss
index 7de7518..aba34ed 100644
--- a/assets/stylesheets/addons/_position.scss
+++ b/assets/stylesheets/addons/_position.scss
@@ -1,4 +1,4 @@
-@mixin position ($position: relative, $coordinates: null null null null) {
+@mixin position ($position: relative, $coordinates: 0 0 0 0) {
 
   @if type-of($position) == list {
     $coordinates: $position;
@@ -14,19 +14,19 @@
 
   position: $position;
 
-  @if ($top and $top == auto) or (type-of($top) == number) {
+  @if ($top and $top == auto) or (type-of($top) == number and not unitless($top)) {
     top: $top;
   }
 
-  @if ($right and $right == auto) or (type-of($right) == number) {
+  @if ($right and $right == auto) or (type-of($right) == number and not unitless($right)) {
     right: $right;
   }
 
-  @if ($bottom and $bottom == auto) or (type-of($bottom) == number) {
+  @if ($bottom and $bottom == auto) or (type-of($bottom) == number and not unitless($bottom)) {
     bottom: $bottom;
   }
 
-  @if ($left and $left == auto) or (type-of($left) == number) {
+  @if ($left and $left == auto) or (type-of($left) == number and not unitless($left)) {
     left: $left;
   }
 }
diff --git a/test/fixtures/features.scss b/test/fixtures/features.scss
index 7b93010..ee22ef8 100644
--- a/test/fixtures/features.scss
+++ b/test/fixtures/features.scss
@@ -299,7 +299,7 @@ $gw-gutter: 40px;
   @include position(relative, 0px 0 0 100px);
   @include position(relative, 0 0 0 0);
   @include position(relative, 0 3em 0 3em);
-  @include position(relative, null null null null);
+  //@include position(relative, null null null null);
 }
 
 .prefixer {