diff --git a/.github/renovate.json b/.github/renovate.json
index 0b63169da5..92ce1a0918 100644
--- a/.github/renovate.json
+++ b/.github/renovate.json
@@ -50,6 +50,11 @@
       "matchManagers": ["gomod"],
       "matchDepTypes": ["golang"],
       "enabled": false
+    },
+    {
+      "description": "Skip releases whose own `go` directive exceeds ours. Without this, `gomodTidy` propagates their requirement into our go.mod and breaks the older Go versions in the CI matrix.",
+      "matchManagers": ["gomod"],
+      "constraintsFiltering": "strict"
     }
   ]
 }
diff --git a/experiments/errors.go b/experiments/errors.go
index 68a5f8b872..850220c4f9 100644
--- a/experiments/errors.go
+++ b/experiments/errors.go
@@ -16,7 +16,7 @@ type InvalidValueError struct {
 
 func (err InvalidValueError) Error() string {
 	return fmt.Sprintf(
-		"task: Experiment %q has an invalid value %q (allowed values: %s)",
+		"task: Experiment %q has an invalid value %d (allowed values: %s)",
 		err.Name,
 		err.Value,
 		strings.Join(slicesext.Convert(err.AllowedValues, strconv.Itoa), ", "),