diff --git a/cmd/ooniprobe/internal/nettests/web_connectivity.go b/cmd/ooniprobe/internal/nettests/web_connectivity.go
index fc752b2..c304701 100644
--- a/cmd/ooniprobe/internal/nettests/web_connectivity.go
+++ b/cmd/ooniprobe/internal/nettests/web_connectivity.go
@@ -9,6 +9,30 @@ import (
 	"github.com/ooni/probe-cli/v3/internal/engine/model"
 )
 
+// preventMistakes makes the code more robust with respect to any possible
+// integration issue where the backend returns to us URLs that don't
+// belong to the category codes we requested.
+func preventMistakes(input []model.URLInfo, categories []string) (output []model.URLInfo) {
+	if len(categories) <= 0 {
+		return input
+	}
+	for _, entry := range input {
+		var found bool
+		for _, cat := range categories {
+			if entry.CategoryCode == cat {
+				found = true
+				break
+			}
+		}
+		if !found {
+			log.Warnf("URL %+v not in %+v; skipping", entry, categories)
+			continue
+		}
+		output = append(output, entry)
+	}
+	return
+}
+
 func lookupURLs(ctl *Controller, categories []string) ([]string, map[int64]int64, error) {
 	inputloader := &engine.InputLoader{
 		CheckInConfig: &model.CheckInConfig{
@@ -29,11 +53,12 @@ func lookupURLs(ctl *Controller, categories []string) ([]string, map[int64]int64
 	}
 	log.Infof("Calling CheckIn API with %s runType", ctl.RunType)
 	testlist, err := inputloader.Load(context.Background())
-	var urls []string
-	urlIDMap := make(map[int64]int64)
 	if err != nil {
 		return nil, nil, err
 	}
+	testlist = preventMistakes(testlist, categories)
+	var urls []string
+	urlIDMap := make(map[int64]int64)
 	for idx, url := range testlist {
 		log.Debugf("Going over URL %d", idx)
 		urlID, err := database.CreateOrUpdateURL(
diff --git a/cmd/ooniprobe/internal/nettests/web_connectivity_test.go b/cmd/ooniprobe/internal/nettests/web_connectivity_test.go
new file mode 100644
index 0000000..5c17c64
--- /dev/null
+++ b/cmd/ooniprobe/internal/nettests/web_connectivity_test.go
@@ -0,0 +1,77 @@
+package nettests
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/ooni/probe-cli/v3/internal/engine/model"
+)
+
+func TestPreventMistakesWithCategories(t *testing.T) {
+	input := []model.URLInfo{{
+		CategoryCode: "NEWS",
+		URL:          "https://repubblica.it/",
+		CountryCode:  "IT",
+	}, {
+		CategoryCode: "HACK",
+		URL:          "https://2600.com",
+		CountryCode:  "XX",
+	}, {
+		CategoryCode: "FILE",
+		URL:          "https://addons.mozilla.org/",
+		CountryCode:  "XX",
+	}}
+	desired := []model.URLInfo{{
+		CategoryCode: "NEWS",
+		URL:          "https://repubblica.it/",
+		CountryCode:  "IT",
+	}, {
+		CategoryCode: "FILE",
+		URL:          "https://addons.mozilla.org/",
+		CountryCode:  "XX",
+	}}
+	output := preventMistakes(input, []string{"NEWS", "FILE"})
+	if diff := cmp.Diff(desired, output); diff != "" {
+		t.Fatal(diff)
+	}
+}
+
+func TestPreventMistakesWithoutCategoriesAndNil(t *testing.T) {
+	input := []model.URLInfo{{
+		CategoryCode: "NEWS",
+		URL:          "https://repubblica.it/",
+		CountryCode:  "IT",
+	}, {
+		CategoryCode: "HACK",
+		URL:          "https://2600.com",
+		CountryCode:  "XX",
+	}, {
+		CategoryCode: "FILE",
+		URL:          "https://addons.mozilla.org/",
+		CountryCode:  "XX",
+	}}
+	output := preventMistakes(input, nil)
+	if diff := cmp.Diff(input, output); diff != "" {
+		t.Fatal(diff)
+	}
+}
+
+func TestPreventMistakesWithoutCategoriesAndEmpty(t *testing.T) {
+	input := []model.URLInfo{{
+		CategoryCode: "NEWS",
+		URL:          "https://repubblica.it/",
+		CountryCode:  "IT",
+	}, {
+		CategoryCode: "HACK",
+		URL:          "https://2600.com",
+		CountryCode:  "XX",
+	}, {
+		CategoryCode: "FILE",
+		URL:          "https://addons.mozilla.org/",
+		CountryCode:  "XX",
+	}}
+	output := preventMistakes(input, []string{})
+	if diff := cmp.Diff(input, output); diff != "" {
+		t.Fatal(diff)
+	}
+}