diff --git a/pkgs/build-support/setup-hooks/multiple-outputs.sh b/pkgs/build-support/setup-hooks/multiple-outputs.sh
index 32d4e065875..2e95495c96f 100644
--- a/pkgs/build-support/setup-hooks/multiple-outputs.sh
+++ b/pkgs/build-support/setup-hooks/multiple-outputs.sh
@@ -9,7 +9,7 @@ _assignFirst() {
     local varName="$1"
     local REMOVE=REMOVE # slightly hacky - we allow REMOVE (i.e. not a variable name)
     shift
-	while (( $# )); do
+    while (( $# )); do
         if [ -n "${!1-}" ]; then eval "${varName}"="$1"; return; fi
         shift
     done