diff --git a/build.ninja.in b/build.ninja.in
index cf585f5..d46df70 100644
--- a/build.ninja.in
+++ b/build.ninja.in
@@ -32,7 +32,7 @@
 builddir = ${g.bootstrap.buildDir}/.minibootstrap
 
 rule g.bootstrap.bootstrap
-    command = ${g.bootstrap.bootstrapCmd} -i ${in} -b ${g.bootstrap.buildDir}
+    command = BUILDDIR=${g.bootstrap.buildDir} ${g.bootstrap.bootstrapCmd} -i ${in}
     description = bootstrap ${in}
     generator = true