diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1452529..3f027cf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 All notable changes to this project will be documented in this file.
 
+## 5.3.0 - 10-november-2021
+
+- Fixed a bug where `px` based media queries were not converted to `em`
+
 ## 5.2.0 - 03-november-2021
 
 - Upgraded stylelint-config-supple to version 4
diff --git a/package-lock.json b/package-lock.json
index 524b5e7..d35a5da 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "@supple-kit/supple-css",
-  "version": "5.2.0",
+  "version": "5.3.0",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
diff --git a/package.json b/package.json
index c8a4081..24cac0b 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@supple-kit/supple-css",
-  "version": "5.2.0",
+  "version": "5.3.0",
   "description": "Reliable and testable Sass framework. Fluid, Variable, supple if you will",
   "main": "index.scss",
   "repository": "https://github.com/supple-kit/supple-css.git",
diff --git a/settings/defaults/_index.scss b/settings/defaults/_index.scss
index 468129f..ef3c32e 100644
--- a/settings/defaults/_index.scss
+++ b/settings/defaults/_index.scss
@@ -115,7 +115,20 @@ $should-be-pixel-values: (
 @each $key, $value in $should-be-pixel-values {
   @if type-of($value) == number {
     @if math.unit($value) != 'px' {
-      @error '`#{$key}: #{$value}` needs to be a pixel value.';
+      @error '`#{$key}: #{$value}` needs to be a pixel unit.';
+    }
+  } @else {
+    @error '`#{$key}: #{$value}` needs to be a number.';
+  }
+}
+
+/**
+ * check that breakpoints are defined in px or em
+ */
+@each $key, $value in $breakpoints {
+  @if type-of($value) == number {
+    @if math.unit($value) != 'px' and math.unit($value) != 'em' {
+      @error 'Breakpoint `#{$key}: #{$value}` needs to be a pixel or em unit.';
     }
   } @else {
     @error '`#{$key}: #{$value}` needs to be a number.';
diff --git a/tools/_internal/_functions.scss b/tools/_internal/_functions.scss
index 970b38b..9d9f05f 100644
--- a/tools/_internal/_functions.scss
+++ b/tools/_internal/_functions.scss
@@ -109,17 +109,17 @@
   $parsed-value: validate-query($value);
 
   @if $parsed-value {
-    @if math.unit($parsed-value) == 'em' {
-      $min-w: $parsed-value;
-    } @else {
+    $resolved-value: $parsed-value;
+
+    @if math.unit($parsed-value) == 'px' {
       @if $key == max-width or $key == max-height {
         $parsed-value: $parsed-value - 1px;
       }
 
-      $min-w: value-to-em($parsed-value);
+      $resolved-value: value-to-em($parsed-value);
     }
 
-    $return: map.merge($return, ($key: $parsed-value));
+    $return: map.merge($return, ($key: $resolved-value));
   }
 
   @return $return;