diff --git a/pkgs/stdenv/generic/setup.sh b/pkgs/stdenv/generic/setup.sh
index c1de5b97d2d6..cc69434dc8c9 100644
--- a/pkgs/stdenv/generic/setup.sh
+++ b/pkgs/stdenv/generic/setup.sh
@@ -1044,7 +1044,7 @@ substituteAllInPlace() {
 # the environment used for building.
 dumpVars() {
     if [ "${noDumpEnvVars:-0}" != 1 ]; then
-        export 2>/dev/null >| "$NIX_BUILD_TOP/env-vars" || true
+        install -m 0600 <(export 2>/dev/null) "$NIX_BUILD_TOP/env-vars" || true
     fi
 }