diff --git a/pkgs/diff-flake/default.nix b/pkgs/diff-flake/default.nix
index 27541ea..1f34abf 100644
--- a/pkgs/diff-flake/default.nix
+++ b/pkgs/diff-flake/default.nix
@@ -23,6 +23,7 @@ stdenvNoCC.mkDerivation {
   '';
 
   cat = "${coreutils}/bin/cat";
+  mktemp = "${coreutils}/bin/mktemp";
   git = "${git}/bin/git";
   sed = "${gnused}/bin/sed";
 
diff --git a/pkgs/diff-flake/diff-flake b/pkgs/diff-flake/diff-flake
index 144685c..7d29f60 100755
--- a/pkgs/diff-flake/diff-flake
+++ b/pkgs/diff-flake/diff-flake
@@ -98,8 +98,8 @@ fill_default_outputs() {
 
 diff_output() {
     local PREV NEW;
-    PREV="$(mktemp --dry-run)"
-    NEW="$(mktemp --dry-run)"
+    PREV="$(@mktemp@ --dry-run)"
+    NEW="$(@mktemp@ --dry-run)"
 
     nix build "${NIX_BUILD_ARGS[@]}" -v ".?rev=${PREVIOUS_REV}#$1" -o "$PREV"
     nix build "${NIX_BUILD_ARGS[@]}" -v ".${NEW_REV:+?rev=$NEW_REV}#$1" -o "$NEW"