diff --git a/pkgs/stdenv/generic/setup.sh b/pkgs/stdenv/generic/setup.sh
index 1eb2ad003d9..3d4ef2e1846 100644
--- a/pkgs/stdenv/generic/setup.sh
+++ b/pkgs/stdenv/generic/setup.sh
@@ -178,7 +178,7 @@ substitute() {
     local input="$1"
     local output="$2"
 
-    local params=("$@")
+    local -a params=("$@")
 
     local sedScript=$NIX_BUILD_TOP/.sedargs
     rm -f $sedScript