diff --git a/src/printer-postcss.js b/src/printer-postcss.js
index 1ecc2907..48149fdc 100644
--- a/src/printer-postcss.js
+++ b/src/printer-postcss.js
@@ -110,7 +110,12 @@ function genericPrint(path, options, print) {
         /^\(\s*\)$/.test(n.params.value);
       return concat([
         "@",
-        isDetachedRulesetCall ? n.name : maybeToLowerCase(n.name),
+        // If a Less file ends up being parsed with the SCSS parser, Less
+        // variable declarations will be parsed as atrules with names ending
+        // with a colon, so keep the original case then.
+        isDetachedRulesetCall || n.name.endsWith(":")
+          ? n.name
+          : maybeToLowerCase(n.name),
         hasParams
           ? concat([
               isDetachedRulesetCall ? "" : " ",
diff --git a/tests/css_case/__snapshots__/jsfmt.spec.js.snap b/tests/css_case/__snapshots__/jsfmt.spec.js.snap
index d23c2747..5a8267bc 100644
--- a/tests/css_case/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/css_case/__snapshots__/jsfmt.spec.js.snap
@@ -42,9 +42,13 @@ a[HREF=KeepAttrValue]:HOVER::FIRST-letter,
   BACKGROUND: RED;
 }
 
+@KeepTopLevelVar: val;
+$KeepScssVar: val;
+
 .Keep(@Keep: 12e03PX) WHEN (@Keep=Case) /*:*/ {
     @KeepVar: KeepName; /*:*/
     @{KeepInterpolationVar}: val;
+    $KeepScssVar: val;
 
     @{Keep}[@{Keep}][@{Keep}^=@{Keep-1A}]:@{Keep} {
       prop: val;
@@ -119,9 +123,13 @@ a[href="KeepAttrValue"]:hover::first-letter,
   background: RED;
 }
 
+@KeepTopLevelVar: val;
+$KeepScssVar: val;
+
 .Keep(@Keep: 12e3px) when (@Keep=Case) {
   @KeepVar: KeepName; /*:*/
   @{KeepInterpolationVar}: val;
+  $KeepScssVar: val;
 
   @{Keep}[@{Keep}][@{Keep}^=@{Keep-1A}]:@{Keep} {
     prop: val;
@@ -206,11 +214,15 @@ a[HREF=KeepAttrValue]:HOVER::FIRST-letter,
     @RETURN 12;
 }
 
+$KeepTopLevelVar: val;
+@KeepLessVar: val;
+
 @MIXIN KeepMixinName($Keep: 15IN, $Keep: $Keep15IN, $Keep: Keep-1E-2Em) {
     $KeepVar: KeepFuncName();
     #{$KeepInterpolationVar}: val;
     #{$Keep + 15PX}: val;
     #{$Keep + $Keep15PX}: val;
+    @KeepLessVar: val;
 
     #{$Keep}[#{$Keep}][#{Keep}^=#{Keep-1A}]:#{$Keep} {
       prop: val;
@@ -286,11 +298,15 @@ a[href="KeepAttrValue"]:hover::first-letter,
   @return 12;
 }
 
+$KeepTopLevelVar: val;
+@KeepLessVar: val;
+
 @mixin KeepMixinName($Keep: 15in, $Keep: $Keep15IN, $Keep: Keep-1E-2Em) {
   $KeepVar: KeepFuncName();
   #{$KeepInterpolationVar}: val;
   #{$Keep + 15PX}: val;
   #{$Keep + $Keep15PX}: val;
+  @KeepLessVar: val;
 
   #{$Keep}[#{$Keep}][#{Keep}^="#{Keep-1A}"]:#{$Keep} {
     prop: val;
diff --git a/tests/css_case/case.less b/tests/css_case/case.less
index 637f13f8..ea33b7c7 100644
--- a/tests/css_case/case.less
+++ b/tests/css_case/case.less
@@ -39,9 +39,13 @@ a[HREF=KeepAttrValue]:HOVER::FIRST-letter,
   BACKGROUND: RED;
 }
 
+@KeepTopLevelVar: val;
+$KeepScssVar: val;
+
 .Keep(@Keep: 12e03PX) WHEN (@Keep=Case) /*:*/ {
     @KeepVar: KeepName; /*:*/
     @{KeepInterpolationVar}: val;
+    $KeepScssVar: val;
 
     @{Keep}[@{Keep}][@{Keep}^=@{Keep-1A}]:@{Keep} {
       prop: val;
diff --git a/tests/css_case/case.scss b/tests/css_case/case.scss
index bc0fe16e..aa02639b 100644
--- a/tests/css_case/case.scss
+++ b/tests/css_case/case.scss
@@ -40,11 +40,15 @@ a[HREF=KeepAttrValue]:HOVER::FIRST-letter,
     @RETURN 12;
 }
 
+$KeepTopLevelVar: val;
+@KeepLessVar: val;
+
 @MIXIN KeepMixinName($Keep: 15IN, $Keep: $Keep15IN, $Keep: Keep-1E-2Em) {
     $KeepVar: KeepFuncName();
     #{$KeepInterpolationVar}: val;
     #{$Keep + 15PX}: val;
     #{$Keep + $Keep15PX}: val;
+    @KeepLessVar: val;
 
     #{$Keep}[#{$Keep}][#{Keep}^=#{Keep-1A}]:#{$Keep} {
       prop: val;