diff --git a/.travis.yml b/.travis.yml
index 432dbd02..f98fed06 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,5 @@
 language: node_js
 node_js:
-  - '11'
+  - '12'
   - '10'
   - '8'
-  - '6'
diff --git a/README.md b/README.md
index 94da9d3d..2fcf8448 100644
--- a/README.md
+++ b/README.md
@@ -70,7 +70,7 @@ comb.processPath('assets/css');
 This project is actively mantained. But anyone and everyone is welcome to contribute.
 Please take a moment to review the [guidelines for contributing](CONTRIBUTING.md).
 
-Also you can become a mantainer. To do that please ping
+Also you can become a maintainer. To do that please ping
 [@tonyganch](https://github.com/tonyganch).
 
 ## Authors
diff --git a/src/options/sort-order.js b/src/options/sort-order.js
index 482e0259..141734b6 100644
--- a/src/options/sort-order.js
+++ b/src/options/sort-order.js
@@ -171,7 +171,10 @@ module.exports = {
 
   _getSortablePropertyName(node) {
     if (node.is('declaration')) {
-      let property = node.first('property').first();
+      let property = node.first('property');
+      if (property === null) property = node.first('customProperty');
+
+      property = property.first();
       return property.is('variable') ? '$variable' : property.content;
     }
 
@@ -382,6 +385,14 @@ module.exports = {
     a = a.node.first().first().content;
     b = b.node.first().first().content;
 
+    if (Array.isArray(a)) {
+      a = a[0].content;
+    }
+
+    if (Array.isArray(b)) {
+      b = b[0].content;
+    }
+
     // Get prefix and unprefixed part. For example:
     // ['-o-animation', '-o-', 'animation']
     // ['color', '', 'color']
diff --git a/test/core/css/test.js b/test/core/css/test.js
new file mode 100644
index 00000000..a3bbbb93
--- /dev/null
+++ b/test/core/css/test.js
@@ -0,0 +1,11 @@
+const Test = require('../core_test');
+
+describe('css', function() {
+  it('Should parse variables', function() {
+    const test = new Test(this);
+
+    test.comb.configure({});
+
+    return test.shouldBeEqual('variable.css');
+  });
+});
diff --git a/test/core/css/variable.css b/test/core/css/variable.css
new file mode 100644
index 00000000..dd6becf9
--- /dev/null
+++ b/test/core/css/variable.css
@@ -0,0 +1,3 @@
+div {
+  --color: red;
+}
diff --git a/test/options/sort-order-fallback/process/scss/leftovers-variable.expected.scss b/test/options/sort-order-fallback/process/scss/leftovers-variable.expected.scss
new file mode 100644
index 00000000..a7d2eca2
--- /dev/null
+++ b/test/options/sort-order-fallback/process/scss/leftovers-variable.expected.scss
@@ -0,0 +1 @@
+div {$blue: steelblue; $red: tomato;  }
diff --git a/test/options/sort-order-fallback/process/scss/leftovers-variable.scss b/test/options/sort-order-fallback/process/scss/leftovers-variable.scss
new file mode 100644
index 00000000..efe7eb6c
--- /dev/null
+++ b/test/options/sort-order-fallback/process/scss/leftovers-variable.scss
@@ -0,0 +1 @@
+div {$red: tomato;  $blue: steelblue; }
diff --git a/test/options/sort-order-fallback/process/test.js b/test/options/sort-order-fallback/process/test.js
index 9127d943..6ef495e0 100644
--- a/test/options/sort-order-fallback/process/test.js
+++ b/test/options/sort-order-fallback/process/test.js
@@ -41,4 +41,15 @@ describe('Option `sort-order-fallback`, process', function() {
       return test.shouldBeEqual('test.css', 'test-3.expected.css');
     });
   });
+
+  describe('scss', function() {
+    it('Should sort leftover variables alphabetically', function() {
+      let config = {
+        'sort-order': [],
+        'sort-order-fallback': 'abc'
+      };
+      let test = new Test(this, config);
+      return test.shouldBeEqual('leftovers-variable.scss', 'leftovers-variable.expected.scss');
+    });
+  });
 });
diff --git a/test/options/sort-order/process/scss/variable.expected.scss b/test/options/sort-order/process/scss/variable.expected.scss
index c17c6341..a7359b10 100644
--- a/test/options/sort-order/process/scss/variable.expected.scss
+++ b/test/options/sort-order/process/scss/variable.expected.scss
@@ -1 +1 @@
-div {$red: tomato;  color: $tomato; }
+div {$red: tomato;  color: $red; }
diff --git a/test/options/sort-order/process/scss/variable.scss b/test/options/sort-order/process/scss/variable.scss
index f759f22c..967fd4f0 100644
--- a/test/options/sort-order/process/scss/variable.scss
+++ b/test/options/sort-order/process/scss/variable.scss
@@ -1 +1 @@
-div { color: $tomato; $red: tomato; }
+div { color: $red; $red: tomato; }