diff --git a/pkgs/tools/networking/kea/default.nix b/pkgs/tools/networking/kea/default.nix
index 8a474812e19..e1829bcaf7d 100644
--- a/pkgs/tools/networking/kea/default.nix
+++ b/pkgs/tools/networking/kea/default.nix
@@ -14,8 +14,8 @@ stdenv.mkDerivation rec {
   patches = [ ./dont-create-var.patch ];
 
   postPatch = ''
-    substituteInPlace ./src/bin/keactrl/Makefile.am '@sysconfdir@' "$out/etc"
-    substituteInPlace ./src/bin/keactrl/Makefile.am '@(sysconfdir)@' "$out/etc"
+    substituteInPlace ./src/bin/keactrl/Makefile.am --replace '@sysconfdir@' "$out/etc"
+    substituteInPlace ./src/bin/keactrl/Makefile.am --replace '@(sysconfdir)@' "$out/etc"
   '';
 
   configureFlags = [