diff --git a/lib/server/readMetadata.js b/lib/server/readMetadata.js
index 61e2582e5672f..f6cd8aad8d81e 100644
--- a/lib/server/readMetadata.js
+++ b/lib/server/readMetadata.js
@@ -162,13 +162,11 @@ function processMetadata(file) {
     throw new Error('Document id cannot include "/".');
   }
 
-  // if file is located in subdirectory,
-  // it will have the directory name appended to it's id
-  const relativeFile = path.relative(
-    path.join(CWD, '../', getDocsPath()),
-    file
+  // If a doc file is located in a subdirectory, prepend the subdir to it's ID
+  // Example: `docs/projectA/test.md` with 'test' ID is changed to `projectA/test`
+  const curDir = path.dirname(
+    path.relative(path.join(CWD, '../', getDocsPath()), file)
   );
-  const curDir = path.dirname(relativeFile);
   if (curDir !== '.') {
     metadata.id = curDir + '/' + metadata.id;
     metadata.source = curDir + '/' + metadata.source;