diff --git a/src/index.js b/src/index.js
index d201e1bc..13925639 100644
--- a/src/index.js
+++ b/src/index.js
@@ -669,7 +669,7 @@ export default class OfflinePlugin {
         relativeBase = relativeBase + '/';
       }
 
-      tool.basePath = relativeBase[0] === '.' ? relativeBase : './' + relativeBase;
+      tool.basePath = relativeBase[0] === '.' ? relativeBase : path.join('./', relativeBase);
     } else if (this.publicPath) {
       tool.basePath = this.publicPath.replace(/\/$/, '') + '/';
     }
@@ -698,7 +698,7 @@ export default class OfflinePlugin {
           return _path;
         }
 
-        return tool.basePath + _path;
+        return path.join(tool.basePath, _path);
       });
     } else {
       tool.pathRewrite = (path => {
@@ -726,7 +726,7 @@ export default class OfflinePlugin {
           return key;
         }
 
-        return this.publicPath + key.replace(/^\.?\//, '');
+        return path.join(this.publicPath, key.replace(/^\.?\//, ''));
       });
   }