diff --git a/guix/scripts/build.scm b/guix/scripts/build.scm
index 9366ab6cccb6645dba6c028d37cfd5853f578d16..da71adba681e6593743ac4d6aa2137db761763c4 100644
--- a/guix/scripts/build.scm
+++ b/guix/scripts/build.scm
@@ -228,7 +228,7 @@ (define (show-help)
   (display (_ "
   -S, --source           build the packages' source derivations"))
   (display (_ "
-  --sources[=TYPE]       build source derivations; TYPE may optionally be one
+      --sources[=TYPE]   build source derivations; TYPE may optionally be one
                          of \"package\", \"all\" (default), or \"transitive\""))
   (display (_ "
   -s, --system=SYSTEM    attempt to build for SYSTEM--e.g., \"i686-linux\""))