diff --git a/pkgs/stdenv/generic/setup.sh b/pkgs/stdenv/generic/setup.sh
index 443e57b065d..eba29beee17 100644
--- a/pkgs/stdenv/generic/setup.sh
+++ b/pkgs/stdenv/generic/setup.sh
@@ -339,7 +339,7 @@ substitute() {
     local n p pattern replacement varName content
 
     # a slightly hacky way to keep newline at the end
-    content="$(cat $input; echo -n X)"
+    content="$(cat "$input"; echo -n X)"
     content="${content%X}"
 
     for ((n = 2; n < ${#params[*]}; n += 1)); do