diff --git a/api/v1beta1/tenant_annotations.go b/api/v1beta1/tenant_annotations.go
index 4f1d3597..31e5a5fa 100644
--- a/api/v1beta1/tenant_annotations.go
+++ b/api/v1beta1/tenant_annotations.go
@@ -5,6 +5,7 @@ package v1beta1
 
 import (
 	"fmt"
+	"strings"
 )
 
 const (
@@ -21,9 +22,9 @@ const (
 )
 
 func UsedQuotaFor(resource fmt.Stringer) string {
-	return "quota.capsule.clastix.io/used-" + resource.String()
+	return "quota.capsule.clastix.io/used-" + strings.ReplaceAll(resource.String(), "/", "_")
 }
 
 func HardQuotaFor(resource fmt.Stringer) string {
-	return "quota.capsule.clastix.io/hard-" + resource.String()
+	return "quota.capsule.clastix.io/hard-" + strings.ReplaceAll(resource.String(), "/", "_")
 }