diff --git a/lib/lost-offset.js b/lib/lost-offset.js
index 39ccadee..12eb58e8 100644
--- a/lib/lost-offset.js
+++ b/lib/lost-offset.js
@@ -111,15 +111,15 @@ module.exports = function lostOffsetDecl(css, settings) {
     } else if (lostOffsetNumerator > 0) {
       if (lostOffsetGutter !== '0') {
         decl.cloneBefore({
-          prop: 'margin-right',
-          value: 'calc(99.9% * '
-          + lostOffset + ' - (' + lostOffsetGutter + ' - '
-          + lostOffsetGutter + ' * ' + lostOffset + ') + ('
-          + lostOffsetGutter + ' * 2)) !important'
+          prop: 'margin-left',
+          value: 'calc(99.9% * (-'
+          + lostOffset + ' * -1) - (' + lostOffsetGutter + ' - '
+          + lostOffsetGutter + ' * (-' + lostOffset + ' * -1)) + '
+          + lostOffsetGutter + ') !important'
         });
       } else {
         decl.cloneBefore({
-          prop: 'margin-right',
+          prop: 'margin-left',
           value: 'calc(99.999999% * ' + lostOffset + ') !important'
         });
       }
@@ -127,9 +127,9 @@ module.exports = function lostOffsetDecl(css, settings) {
       if (lostOffsetGutter !== '0') {
         decl.cloneBefore({
           prop: 'margin-left',
-          value: 'calc(99.9% * ('
-          + lostOffset + ' * -1) - (' + lostOffsetGutter + ' - '
-          + lostOffsetGutter + ' * (' + lostOffset + ' * -1)) + '
+          value: 'calc(99.9% * '
+          + lostOffset + ' - (' + lostOffsetGutter + ' - '
+          + lostOffsetGutter + ' * ' + lostOffset + ') + '
           + lostOffsetGutter + ') !important'
         });
       } else {
diff --git a/test/lost-offset.js b/test/lost-offset.js
index 2c8c9255..e2eb90a8 100644
--- a/test/lost-offset.js
+++ b/test/lost-offset.js
@@ -6,7 +6,7 @@ describe('lost-offset', function() {
   it('moves element to the left', function() {
     check(
       'a { lost-offset: 1/3; }',
-      'a { margin-right: calc(99.9% * 1/3 - (30px - 30px * 1/3) + (30px * 2)' +
+      'a { margin-left: calc(99.9% * (-1/3 * -1) - (30px - 30px * (-1/3 * -1)) + 30px' +
       ') !important; }'
     );
   });
@@ -14,8 +14,8 @@ describe('lost-offset', function() {
   it('moves element to the right', function() {
     check(
       'a { lost-offset: -1/3; }',
-      'a { margin-left: calc(99.9% * (-1/3 * -1) - (30px - 30px * ' +
-      '(-1/3 * -1)) + 30px) !important; }'
+      'a { margin-left: calc(99.9% * -1/3 - (30px - 30px * ' +
+      '-1/3) + 30px) !important; }'
     );
   });
 
@@ -38,8 +38,8 @@ describe('lost-offset', function() {
   it('supports custom gutter', function() {
     check(
       'a { lost-offset: 1/2 row 60px; }',
-      'a { margin-right: calc(99.9% * 1/2 - (60px - 60px * 1/2) + ' +
-      '(60px * 2)) !important; }'
+      'a { margin-left: calc(99.9% * (-1/2 * -1) - (60px - 60px * (-1/2 * -1)) + ' +
+      '60px) !important; }'
     );
   });
 });