diff --git a/lib/appenders/file.js b/lib/appenders/file.js
index 6ea01ca..c6be910 100644
--- a/lib/appenders/file.js
+++ b/lib/appenders/file.js
@@ -54,6 +54,14 @@ function fileAppender (file, layout, logSize, numBackups) {
         function increaseFileIndex (fileToRename) {
             var idx = index(fileToRename);
             if (idx < numBackups) {
+                //on windows, you can get a EEXIST error if you rename a file to an existing file
+                //so, we'll try to delete the file we're renaming to first
+                try {
+                    fs.unlinkSync(file + '.' + (idx+1));
+                } catch (e) {
+                    //couldn't delete, but that could be because it doesn't exist
+                    //try renaming anyway
+                }
                 fs.renameSync(path.join(path.dirname(file), fileToRename), file + '.' + (idx + 1));
             }
         }