diff --git a/doc/installation/from-source.en-us.md b/doc/installation/from-source.en-us.md
index e0be7f2f..dfded3d9 100644
--- a/doc/installation/from-source.en-us.md
+++ b/doc/installation/from-source.en-us.md
@@ -132,6 +132,8 @@ If pre-built frontend files are present it is possible to only build the backend
 TAGS="bindata" make backend
 ```
 
+Webpack source maps are by default enabled in development builds and disabled in production builds. They can be enabled by setting the `ENABLE_SOURCEMAP=true` environment variable.
+
 ## Test
 
 After following the steps above, a `gitea` binary will be available in the working directory.