diff --git a/packages/gatsby/src/services/initialize.ts b/packages/gatsby/src/services/initialize.ts
index 92745145b5d41..0609b1055b943 100644
--- a/packages/gatsby/src/services/initialize.ts
+++ b/packages/gatsby/src/services/initialize.ts
@@ -35,7 +35,10 @@ interface IPluginResolutionSSR extends IPluginResolution {
 if (
   process.env.gatsby_executing_command === `develop` &&
   process.env.GATSBY_EXPERIMENTAL_FAST_DEV &&
-  !isCI()
+  !isCI() &&
+  // skip FAST_DEV handling in workers, all env vars will be handle
+  // by main process already and passed to worker
+  !process.env.GATSBY_WORKER_POOL_WORKER
 ) {
   process.env.GATSBY_EXPERIMENTAL_DEV_SSR = `true`
   process.env.PRESERVE_FILE_DOWNLOAD_CACHE = `true`