diff --git a/packages/postcss-merge-longhand/src/__tests__/borders.js b/packages/postcss-merge-longhand/src/__tests__/borders.js
index 13591b47a..39e99bc11 100644
--- a/packages/postcss-merge-longhand/src/__tests__/borders.js
+++ b/packages/postcss-merge-longhand/src/__tests__/borders.js
@@ -1196,6 +1196,13 @@ test(
   )
 );
 
+test(
+  'Should preserve border rule with only custom properties #1051',
+  passthroughCSS(
+    'h1{border-color: var(--a) var(--b) var(--c) var(--d);border-style:solid;border:var(--fooBar));}'
+  )
+);
+
 test(
   'should overwrite some border-width props and save fallbacks and preserve case #648 2',
   processCSS(
diff --git a/packages/postcss-merge-longhand/src/lib/decl/borders.js b/packages/postcss-merge-longhand/src/lib/decl/borders.js
index f5cf63960..6817af391 100644
--- a/packages/postcss-merge-longhand/src/lib/decl/borders.js
+++ b/packages/postcss-merge-longhand/src/lib/decl/borders.js
@@ -55,7 +55,7 @@ function getLevel(prop) {
 const isValueCustomProp = (value) => value && !!~value.search(/var\s*\(\s*--/i);
 
 function canMergeValues(values) {
-  return !values.some(isValueCustomProp) || values.every(isValueCustomProp);
+  return !values.some(isValueCustomProp);
 }
 
 function getColorValue(decl) {