diff --git a/.changeset/neat-trees-taste.md b/.changeset/neat-trees-taste.md
new file mode 100644
index 0000000..52c4f23
--- /dev/null
+++ b/.changeset/neat-trees-taste.md
@@ -0,0 +1,5 @@
+---
+"vite-plugin-stylex": patch
+---
+
+Make vite-plugin-stylex run in production mode only when the command is "build". Fixes #42.
diff --git a/packages/vite-plugin-stylex/src/index.mts b/packages/vite-plugin-stylex/src/index.mts
index d219580..d2b027a 100644
--- a/packages/vite-plugin-stylex/src/index.mts
+++ b/packages/vite-plugin-stylex/src/index.mts
@@ -152,8 +152,7 @@ export default function styleXVitePlugin({
   return {
     name: "vite-plugin-stylex",
 
-    config(config, env) {
-      isProd = env.mode === "production" || config.mode === "production";
+    config(config) {
       assetsDir = config.build?.assetsDir || "assets";
       publicBasePath = config.base || "/";
     },
@@ -161,6 +160,7 @@ export default function styleXVitePlugin({
     configResolved(config) {
       config.optimizeDeps.exclude = config.optimizeDeps.exclude || [];
       config.optimizeDeps.exclude.push("@stylexjs/open-props");
+      isProd = config.command === "build";
 
       for (const viteAlias of config.resolve.alias) {
         if (typeof viteAlias.find === "string") {