diff --git a/cmd/karma/autocomplete.go b/cmd/karma/autocomplete.go
index b3244eab3..273ab61ac 100644
--- a/cmd/karma/autocomplete.go
+++ b/cmd/karma/autocomplete.go
@@ -45,11 +45,7 @@ func knownLabelNames(c *gin.Context) {
 		sort.Strings(acData)
 	}
 
-	data, err := json.Marshal(acData)
-	if err != nil {
-		log.Error(err.Error())
-		panic(err)
-	}
+	data, _ = json.Marshal(acData)
 
 	apiCache.Set(cacheKey, data, time.Second*15)
 
@@ -80,11 +76,7 @@ func knownLabelValues(c *gin.Context) {
 	values := alertmanager.DedupKnownLabelValues(name)
 	sort.Strings(values)
 
-	data, err := json.Marshal(values)
-	if err != nil {
-		log.Error(err.Error())
-		panic(err)
-	}
+	data, _ = json.Marshal(values)
 
 	apiCache.Set(cacheKey, data, time.Second*15)
 
diff --git a/cmd/karma/proxy_test.go b/cmd/karma/proxy_test.go
index 8b6e31a88..c35a4697e 100644
--- a/cmd/karma/proxy_test.go
+++ b/cmd/karma/proxy_test.go
@@ -1206,3 +1206,22 @@ func TestProxySilenceACL(t *testing.T) {
 		})
 	}
 }
+
+func TestNewAlertmanagerProxyWithInvalidURL(t *testing.T) {
+	am := alertmanager.Alertmanager{URI: "%gh&%ij"}
+	proxy, err := NewAlertmanagerProxy(&am)
+	if err == nil {
+		t.Errorf("NewAlertmanagerProxy didn't return any error")
+	}
+	if proxy != nil {
+		t.Errorf("NewAlertmanagerProxy returned a proxy instance: %v", proxy)
+	}
+}
+
+func TestSetupRouterProxyHandlersWithInvalidURL(t *testing.T) {
+	am := alertmanager.Alertmanager{URI: "%gh&%ij"}
+	err := setupRouterProxyHandlers(nil, &am)
+	if err == nil {
+		t.Errorf("setupRouterProxyHandlers didn't return any error")
+	}
+}