diff --git a/flake.nix b/flake.nix
index ee51b97..c22746d 100644
--- a/flake.nix
+++ b/flake.nix
@@ -99,6 +99,13 @@
                   };
                 };
               }
+              {
+                name = "pretty-unit";
+                format = "pretty";
+                pos = __curPos;
+                expected = pkgs.hello;
+                actual = pkgs.hello;
+              }
               {
                 name = "test-drv";
                 pos = __curPos;
diff --git a/lib/default.nix b/lib/default.nix
index 79fec2b..458fdc8 100644
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -19,9 +19,14 @@
       if format == "json"
       then actual
       else lib.generators.toPretty {} actual;
+    expected' =
+      if format == "json"
+      then expected
+      else lib.generators.toPretty {} expected;
   in {
-    inherit type name description expected;
+    inherit type name description;
     actual = actual';
+    expected = expected';
     # discard string context, otherwise it's being built instantly which we don't want
     actualDrv = builtins.unsafeDiscardStringContext (actualDrv.drvPath or "");
     pos =