diff --git a/l3build.lua b/l3build.lua
index 62a20bd6..32fe004e 100644
--- a/l3build.lua
+++ b/l3build.lua
@@ -64,11 +64,11 @@ end
 maindir = maindir or "."
 
 -- Substructure files
-docfiledir    = docfiledir    or maindir
+docfiledir  = docfiledir  or maindir
 sourcefiledir = sourcefiledir or maindir
-supportdir    = supportdir    or maindir     .. "/support"
-testfiledir   = testfiledir   or maindir     .. "/testfiles"
-testsuppdir   = testsuppdir   or testfiledir .. "/support"
+supportdir  = supportdir  or maindir     .. "/support"
+testfiledir = testfiledir or maindir     .. "/testfiles"
+testsuppdir = testsuppdir or testfiledir .. "/support"
 
 -- Structure within a development area
 builddir   = builddir   or maindir .. "/build"