1 files changed, 2 insertions, 0 deletions
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 676ad5856b13..9c408e29c06c 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -2193,6 +2193,7 @@ void DerivationGoal::startBuilder()
         userNamespaceSync.create();
 
         options.allowVfork = false;
+        options.restoreMountNamespace = false;
 
         Pid helper = startProcess([&]() {
 
@@ -2259,6 +2260,7 @@ void DerivationGoal::startBuilder()
 #endif
     {
         options.allowVfork = !buildUser && !drv->isBuiltin();
+        options.restoreMountNamespace = false;
         pid = startProcess([&]() {
             runChild();
         }, options);