diff --git a/lib/strings.nix b/lib/strings.nix
index 848e61a65ddf..d6170fdf39e3 100644
--- a/lib/strings.nix
+++ b/lib/strings.nix
@@ -337,7 +337,6 @@ rec {
 
   /**
     Concatenate a list of strings, adding a newline at the end of each one.
-    Defined as `concatMapStrings (s: s + "\n")`.
 
     # Inputs
 
@@ -361,7 +360,7 @@ rec {
 
     :::
   */
-  concatLines = concatMapStrings (s: s + "\n");
+  concatLines = str: concatStringsSep "\n" str + "\n";
 
   /**
     Given string `s`, replace every occurrence of the string `from` with the string `to`.