diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 90bcccd24..d768d4429 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -1895,7 +1895,7 @@ void DerivationGoal::startBuilder()
            build user. */
         Path chrootStoreDir = chrootRootDir + settings.nixStore;
         createDirs(chrootStoreDir);
-        chmod_(chrootStoreDir, 0730);
+        chmod_(chrootStoreDir, 0735);
 
         if (chown(chrootStoreDir.c_str(), 0, buildUser.getGID()) == -1)
             throw SysError(format("cannot change ownership of ‘%1%’") % chrootStoreDir);